You may have seen all over Facebook lately a meme about the allegedly terrible Common Core math standards that evil President Obama is imposing on innocent school children that supposedly teaches them a completely convoluted way of doing addition and subtraction. It looks like this:

The right wing is throwing a major league tantrum over this. Hemant Mehta, who actually teaches math, debunks the whole thing.

On the surface, it seems ridiculous. The top makes sense; the bottom is silly;

screw you, Common Core!Except that the top

doesn’tmake sense, the bottomdoes, and the connection to Common Core is completely misunderstood. (Says this math teacher.)Here’s what’s going on: The top is how most of us learned subtraction. I’m sure your teachers taught you what was going on mathematically, but do you really remember what they said? Probably not. For us, it’s just an algorithm. You can do it without thinking. You hope there’s no “borrowing” of numbers involved, but if you had to do it by hand, you could probably pull it off.

The problem with that method is that if I ask students to explain why it works, they’d have a

reallyhard time explaining it to me. They might be able to do the computation, but they don’t get the math behind it. For some people, that’s fine. For math teachers, that’s a problem because it means a lot of students won’t be able to grasp other math concepts in the future because they never really developed “number sense.”…I know. That’s still ridiculous. Well, consider this: Suppose you buy coffee and it costs $4.30 but all you have is a $20 bill. How much change should the barista give you back? (Assume for a second the register is broken.)…

Instead, you’d just figure it out this way: It’d take 70 cents to get to $5… and another $15 to get to $20… so you should get back $15.70.

That’s it. That’s the sort of math most of us do on a regular basis and it’s

exactlythe sort of thinking the “new” way in the picture is attempting to explain. Granted that was an *awful* example to use, but that’s the idea. If students can get a handle on thinkingthisway instead of just plugging numbers into a formula, the thinking goes, it’ll make other math skills much easier to understand.

He also points out that this is not mandated by Common Core at all, it’s just the way some states and local school districts are implementing the standards. But those are facts, so they won’t matter one bit to the right wing.

## 53 comments

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## Gregory in Seattle

March 12, 2014 at 10:48 am (UTC -4) Link to this comment

There are plenty of good reasons to oppose Common Core. The right wingers don’t use any of them: lies serve their agenda far better than the truth ever will.

## doublereed

March 12, 2014 at 10:49 am (UTC -4) Link to this comment

That’s actually not the answer I had in mind, because the book I got this problem out of wants you to do it in Base 8.

## doublereed

March 12, 2014 at 10:51 am (UTC -4) Link to this comment

Oh wait the answer is the same in base 8. Damn.

## Gregory in Seattle

March 12, 2014 at 10:53 am (UTC -4) Link to this comment

@doublereed #2 – Obligatory video

## cswella

March 12, 2014 at 10:54 am (UTC -4) Link to this comment

Almost all the math I do on a daily basis I learned from Arthur Benjamin’s recorded courses. Until I learned the new way, i hated math and avoided it.

## David C Brayton

March 12, 2014 at 11:02 am (UTC -4) Link to this comment

I’m a bit of a maths nerd. Every few years, I’ll see someone propose a totally new way of doing something. About ten years ago, I saw a book that used triangles for ‘trigonometry’. It is

so much easierthan the ratios and tables. obviously, it will never be adopted because the ratio method is more widely adopted than even the metric system. But it should be.I never realized it until just now, but the new way is the method i use most often for simple subtraction. Borrowing 10 from the next column is hard to keep track of mentally.

## Chiroptera

March 12, 2014 at 11:13 am (UTC -4) Link to this comment

It’s been so long since I was in grade school that I don’t remember any of the explanations for why the common arithmetic algorithms work (or if my grade school teachers even explained it to us). It wasn’t until I taught a course for elementary education majors that I even thought to ask the question. Yeah, there is a reason the algorithms work. (The students hated the course, but I found it one of the more interesting subjects I’ve taught.)

## smhll

March 12, 2014 at 11:15 am (UTC -4) Link to this comment

I think the right wing likes poorly understood algorithms handed down by teachers, because one is almost forced to have blind faith in the algorithm rather than understanding the manipulations and relying on one’s own mind.

## eric

March 12, 2014 at 11:21 am (UTC -4) Link to this comment

As Hemant says, the method is good but the example is terrible. First, because people will probably not use this method to do basic subtraction with small abstract numbers

at all. They’ll use it to make change. So why not just us a money example like Hemant does? Second problem: nobody is going to do steps 1 and 2 separately in their head. Our numbering system is base 10 and so the natural thing to do is to add to the nearest 10, not nearest 5.## dean

March 12, 2014 at 11:21 am (UTC -4) Link to this comment

I have also been getting emails from relatives who oppose common core, and seeing postings, stating that teaching of cursive writing is not mandated in the Common Core guidelines so children won’t be able to read the Declaration of Independence (or Constitution, or both, depending on which version of the message is forwarded).

I think I heard this particular (cursive) conspiracy stated long before Common Core – it seems that the people pushing it simply found a new boogey man to attach it to.

## A Hermit

March 12, 2014 at 11:23 am (UTC -4) Link to this comment

The second method there is the one everyone who has ever worked as a cashier uses to make change. Much easier in the field…

## D. C. Sessions

March 12, 2014 at 11:27 am (UTC -4) Link to this comment

The fact is that there are nine and sixty ways of composing tribal lays,

and every single one of them is right.One of my sons just came up with a new algorithm for performing some rather esoteric calculations in mathematical physics (proof has been reviewed and will be published.) He came up with it because the old method drove him nuts — to him it was just ugly, painful, and impossible to follow without notes — which he wouldn’t be able to use for his comprehensive exams. So he came up with a better way.

Which (proud papa moments aside) illustrates one of my longstanding observations about teaching: different people benefit from different approaches. For some, the textbook approach (whichever textbook you use) works fine. For others, it just doesn’t connect, but a different (and equally valid) one gets the idea across beautifully.

A good teacher knows how to make the most of an approach. A great teacher knows lots of approaches and will keep trying them until they find the one that works for each student.

## Robert B.

March 12, 2014 at 11:48 am (UTC -4) Link to this comment

I’ve taught the new way for years, and I’m thrilled to see it in wider usage. Though I’d never have a student write it like that, I’d use a number line, or if the student was more experienced, I’d have them work it out verbally/mentally.

Also, if a kid has to go from 12 to 20 in two steps, he’s in trouble. Better go back and review complements of ten.

## Area Man

March 12, 2014 at 12:04 pm (UTC -4) Link to this comment

How do you reason with people who can only see the world in terms of paranoid conspiracies?

## dingojack

March 12, 2014 at 12:26 pm (UTC -4) Link to this comment

Area Man -”How do you reason with people who can only see the world in terms of paranoid conspiracies?”

Phase one, point and laugh.

Phase two, bathe in the sweet, sweet tears of their utter desolation once their attempt to hijack reality has failed.

Dingo

## Gregory in Seattle

March 12, 2014 at 12:30 pm (UTC -4) Link to this comment

@dean #10 – Cursive has been dead for years: I stopped using it in 6th grade, and I don’t think my younger brothers were ever taught (they graduated high school about 10 years ago.) But not read the Constitution? It was written with a quill pen in an Italic hand, not with a pencil using the Palmer or D’Nealian script. The Constitution and other founding documents remain legible, and the Right Wing has made absolutely sure that there are more than enough typeset printed copies available for anyone who wants them.

I’m much more concerned that literature is not a part of the standard, which means that most schools are either touching on it lightly or not teaching it at all. That is going to have a far more negative impact than the lack of cursive.

## fifthdentist

March 12, 2014 at 12:43 pm (UTC -4) Link to this comment

“But those are facts, so they won’t matter one bit to the right wing.”

Preposterous!!! How can they deny the facts if they don’t know what they are?

## Azkyroth Drinked the Grammar Too :)

March 12, 2014 at 12:51 pm (UTC -4) Link to this comment

“Common Core doesn’t include cursive!” If only. It’s an annoying waste of time with very little practical function.

## tubi

March 12, 2014 at 12:55 pm (UTC -4) Link to this comment

Re: cursive.

My kids are in 1st and 3rd grade currently and neither one knows how to read cursive. It’s not really a big deal, not much is in cursive these days*, and you can read virtually ANY historical document via an online transcription. Although, as with the Bible, it’s better to try to read the original. Hard to anticipate what transcription errors may have occurred, or what’s the right-wing has caused to be omitted.

*The only issue we’ve faced was when my daughter was reading a “My Little Pony” book that featured a hand-written note that one pony had left for another. It was in cursive/script and she had to have me read it to her.

## eric

March 12, 2014 at 12:58 pm (UTC -4) Link to this comment

Polite brush off.

[paranoid rant]

“Wow, I never thought of it that way. Let me think on it further. Goodbye.”

## M can help you with that.

March 12, 2014 at 1:12 pm (UTC -4) Link to this comment

Robert B @ 13 –

Which means developing a sense of how numbers

relateto each other, which iswhat math is all aboutin the first place.There seems to be this conservative fetish for following instructions, including algorithms; the clinging to particular forms of early math education seems to be related to this. It’s as if math is about knowing algorithms to get answers, which is completely off; math is all about the relationships between carefully-defined concepts (numbers, shapes, spaces) based on carefully-defined basic patterns. (Hell, you can go through whole important, elegant, beautiful proofs in math with very few specific numbers; most of the important parts of the field can be described without any specific numerical values beyond the Big Five of 0, 1, e, i, and π.)

There are certainly issues with how math is taught; but these right-wing objections to easier algorithms for basic mathematical operations that actually make more sense in terms of the underlying structure are pushing in exactly the

wrongdirection. (Subtraction by adding is packing 1-dimensional balls of radius (10^n)/2 into a given interval…which, in addition to being the easy way, actually has some mathematical significance.)## jd142

March 12, 2014 at 1:14 pm (UTC -4) Link to this comment

Apparently I’m really weird, because I don’t use either algorithm for things like making change. It’s only for making change though. Buy something for 13.78 and give the clerk $20.00.

Start at the right most non-zero number. What do you add to that number to make 10. Right most number is 8, so 2. ->00.02

Next number, what does it take to get to 10 and subtract 1. Next is 7, so 3, minus 1 is 2 -> 00.22.

Next is 3, so 10-3=7-1=6. -> 06.22

Final number is 2, and in this case both it and 3 are in the same 10 columns. Is the number in the previous column bigger than the one you subtracted? In this case is 0>=3? No, so subtract 1 from 2, then 1-1=0 -> change is $6.22.

If I had given the clerk 25 dollars, then 5>=3, so 2-1=1, so change would have been 11.22.

It’s easier for me to do than to explain.

I’m old and was taught the “borrow from the next column” method.

@Chiroptera – #7 – is the reason the old way works is that you are just borrowing 10 from the column to the left? That’s the only explanation I was given that I can remember and it is the only way I could explain for why it works. So if we had 32-14 (because I wanted a larger number in the ones column for the number being subtracted. 2>4, so “borrow” 10 from the next column. 12-4 is 8. We borrowed 10 from from the tens column, so 3 becomes 2. 2-1 is 1. So 32-14 is 18. It’s something that is so basic we forget how to explain it. Like I know I used to know the proof that in Euclidean geometry, 2 parallel lines never meet. Now I just go, duh, that’s the definition of parallel lines.

## Dunc

March 12, 2014 at 1:25 pm (UTC -4) Link to this comment

It can’t just be that, because here’s they’re screaming about just using a different algorithm. It’s more like they think that however they were taught something is the One True Way to teach that thing, and any deviation is some kind of heresy.

## D. C. Sessions

March 12, 2014 at 1:26 pm (UTC -4) Link to this comment

It seems to be making a minor comeback. My new tablet computer (a Galaxy Note) does such a splendid job of handwriting recognition that cursive is the most efficient input method. I’m slowly relearning the script that I was so bad at more than fifty years ago.

## ianken

March 12, 2014 at 1:37 pm (UTC -4) Link to this comment

The folks who devised this particular method may master math but they have no experience trying to teach this to second graders. That’s a common issue work common core. Technical nerds cook up a new way to do things without accounting for the audience.

## Menyambal

March 12, 2014 at 1:40 pm (UTC -4) Link to this comment

I like the new way, there. It is the same as counting on your fingers, as kids do at one stage. It is counting upwards, which is easier than counting down. And it counts by fives and tens, which is faster, and which leads to multiplication. It really gives a sense of understanding the idea of math, not just a ritual.

I’m going to work out a finger method for this ….

## Nick Gotts

March 12, 2014 at 1:45 pm (UTC -4) Link to this comment

Tell them the old way was invented by Saul Alinsky?

## Steve Morrison

March 12, 2014 at 2:02 pm (UTC -4) Link to this comment

But—but—that would BRAINWASH KIDS WITH MORAL RELATIVISM!!!!! Math with letters instead of numbers is evil!!!!!

It’s just as Ed always says; the real wingnuts are found in the state legislatures.

## Menyambal

March 12, 2014 at 2:05 pm (UTC -4) Link to this comment

Easy-peasy!

How to do the new way on your fingers.

Your right hand is ones, your left hand is fives.

Count from 12 up until you reach a five, namely 15. That’ll be three fingers. Switch to your left and count by fives until you close in on 32, that’ll be three fingers. Switch back to the right, and finish counting up to 32. That’s five fingers on the right, so throw them to one finger on the left. Count the left by fives, and it’s 20.

I don’t see that as being any harder than the old method, and the finger-counting is what kids do already.

I can improve that before I try it on the special-ed boys. I know a couple that could really use it.

## Hatchetfish

March 12, 2014 at 2:17 pm (UTC -4) Link to this comment

Not that the old way doesn’t have its uses, no one wants to go through the new way for 432125.2324-23490.87. That’s why Ada Lovelace gave us calculators. ;) (Says a 31 year old engineer happy to rely on a TI89 and Mathematica and at an utter loss if asked to do long division.)

As for cursive, I use it routinely (though not for work) because

for meit’s faster and less fatiguing, particularly when compared to equivalently legible printing. Make what you will of what that says about my skill with print handwriting, but mostly cursive has the advantage of fewer stops and starts and sharp turns, meaning fewer sharp muscle actions, and a significantly longer time before my hand gets tired writing. That said, if I can, I’ll type before picking up a pen or pencil at all. (I’m a lazy Dvorak user, too.)## Menyambal

March 12, 2014 at 2:51 pm (UTC -4) Link to this comment

Yeah, my finger-counting way worked for the example, but it’ll need some serious tweakage.

Cursive? It’s over two decades now since I took some admissions test where they wanted an essay written in cursive, and I just flat couldn’t do it. Hadn’t used it, haven’t needed it. I write a small, neat print, and can do it fast enough and everyone can read it.

Number-handling happens ‘way more often than reading cursive.

## Hercules Grytpype-Thynne

March 12, 2014 at 3:25 pm (UTC -4) Link to this comment

Everything old is new again. When I was young (years and years and years and years and years ago), it was common for a cashier to count back change exactly that way: if you bought something for, say, $3.46 and handed the cashier a five, the cashier might say “three forty-six”, hand you four pennies and say “three fifty”, hand you two quarters and say “four”, then hand you a dollar bill and say “and one makes five”. This hardly ever happens these days; the cashier just hands you however much change the register says to. It’s very odd that the conservatives are upset that some schools are thinking of bringing back an old and time-honored method.

## Pierce R. Butler

March 12, 2014 at 3:31 pm (UTC -4) Link to this comment

How will kids who never learn cursive sign checks, contracts, etc? Block printing is too easily forged.

## Modusoperandi

March 12, 2014 at 3:57 pm (UTC -4) Link to this comment

Pah! New is bad. That’s why I still stick to Roman Numerals. No zeroes, either.

Pierce R. Butler“How will kids who never learn cursive sign checks…”What’s are “checks”?

“…contracts, etc?”You don’t need to know cursive to sign a good signature. That’s because signatures are illegible.

## Pierce R. Butler

March 12, 2014 at 4:08 pm (UTC -4) Link to this comment

Modusoperandi – So how can the kids create illegible signatures if they can’t write illegible cursive?

## Chiroptera

March 12, 2014 at 4:12 pm (UTC -4) Link to this comment

Several things really stand out for me on this thread.

(1) Some people rarely, if ever, write pages of text by hand. Not that there is anything wrong with that, but I just cannot imagine my life without writing long hand. It’s not a question of “harder” or “easier” than typing, it’s that I enjoy the activity of writing by hand.

Ah, well, in that case I can see that some people enjoy different things than I do. Just strange to me, like people who like cooked carrots or who don’t like coffee.

(2) People who do write by hand find block printing easier than cursive. That is really mind boggling to me. I guess some people have different skill sets. Different people find different things easier and other things harder than I do. But it still seems strange to me.

(3) People think that school curricula should be based on what

theyfind difficult or unnecessary. There were a lot of things I found either difficult when I was in school and ultimately not very useful to me later on. It never occurred to me to suggest that those things should be removed from the curriculum. I always figured that the whole point of a liberal arts education was to expose students to a wide range of stuff and the individuals would decide for themselves what they found interesting and useful.If grade school never taught me cursive, no one else would have. It probably would never occur to me to go and pick up for myself. I feel that my life would be that much poorer for it.

## jaybee

March 12, 2014 at 4:19 pm (UTC -4) Link to this comment

Many cashiers who use the “new way” day in and day don’t completely understand what they are doing. I hate pennies and coins in general, so I work to minimize how many I have. If a purchase totals $3.88, I’ll give the cashier $4.13. This way I give away four or five coins and get one quarter in return. As often as not, if the cashier is making change in their head, they refuse the 13 cents and insist on giving me 12 cents change.

## moarscienceplz

March 12, 2014 at 5:28 pm (UTC -4) Link to this comment

I get the argument for the “new” way, but I don’t get why the first step isn’t 12 + 8 = 20. Is it asking too much to expect that people memorize all the sums from 1 to 20?

## moarscienceplz

March 12, 2014 at 5:33 pm (UTC -4) Link to this comment

@#34 Modusoperandi:

Cuneiform in wet clay! All the way! All the way!

## Peter B

March 12, 2014 at 7:07 pm (UTC -4) Link to this comment

All those annoying position velocity and acceleration problems can be solved without a bunch of hard to remember formulas.

~~Draw a graph~~Make a picture. Start at the bottom left (“origin” to math types) and label increasing height as velocity. Also from the bottom left label increasing time. Draw the problem steps on the picture. The area below the line is your position. Example: 2 hours at 50 miles per hour is 100 miles. If the area of a rectangle is a mystery you are in the wrong class.If the problem speaks of increasing velocity a.k.a. acceleration draw a line diagonally upward. You will, horror of horrors, need to know about the area of triangles.

Be sure that if velocity in feet / second that the horizontal is in seconds. And don’t let anybody tell you that this method is related to calculus.

FWIW, My sister took “New Math” in high school. In that class the logarithm of whatever was defined as the area under the unit hyperbola from 1 to whatever. I am two years older and had the college math that allowed me understand. Our parents had no clue.

## gardengnome

March 12, 2014 at 7:22 pm (UTC -4) Link to this comment

Provided you come up with the correct answer does it matter what method you use? Mathematics, as opposed to arithmetic, was always a mystery to me and remains so, it was one subject I was certain of failing every year in school.

On the other hand, I joined the Post Office after school and, in those pre-calculator days, my mental arithmetic behind the counter was formidably accurate and quick.

## D. C. Sessions

March 12, 2014 at 7:56 pm (UTC -4) Link to this comment

But it is. You’re just describing a geometric approach to calculus. Which (see my comment above) is one of the nine and sixty ways.

## jimatkins

March 12, 2014 at 9:02 pm (UTC -4) Link to this comment

I’m a math teacher, and we are converting to CC next year. I have to teach two (or three) new classes in a completely new way, but I’m looking forward to it. CC stresses getting the answer (however) over rote memorization of techniques. You know all those countries that kick our butts on math scores? They teach math this way. The big change is in high school. We are going to Integrated classes, not the traditional Alg, Geo, Alg 2 pathway. When a subject like conic sections comes up, we teach the algebra and the geometry together. Hey- i’m counting down to retirement, but I’m learning new tricks.

## smrnda

March 12, 2014 at 9:31 pm (UTC -4) Link to this comment

On change and cashiers – if a person is using a calculator, by all means hand them some extra change so you get back a quarter instead of some pennies and smaller counts, but please, don’t pull that on some overworked stiff who’s been standing behind the register for hours and hours. This has nothing to do with their intelligence, just that it’s a rather draining job that saps one’s ability to think and anything confusing can be really disorienting.

On math in general, there are many methods of teaching and many methods of solving things, so I don’t get this particular freak-out. My main problem is that we seem rather obsessed with kids doing arithmetic. I think kids should get how to do this, but I really see no point to long division with huge numbers as it means that you spend years just doing slightly harder arithmetic problems when the kids could move on to higher level math with the aid of a calculator when necessary.

## Hatchetfish

March 13, 2014 at 1:38 am (UTC -4) Link to this comment

Certainly true, Chiroptera, all three observations. I find 1 and 2 as surprising. Particularly that someone would want to hack their way through a written page printing it. My hand cramps thinking about it. Point 3 just seems like a symptom of “pedagogical teleology syndrome” that grips US culture so tightly: school is for working, as surely as the internet is for —-, and nothing not immediately relevant to increasing employer profits should be taught. Hence the reasoning that “90% of minimum wage slaves don’t need anything beyond arithmetic*, so why are we teaching it, and why are we bothering to teach arithmetic so they’ll understand that other stuff they don’t need anyway?”

* Statistic pulled from nether regions for purposes of illustration only.

Smrdna:

“no point to long division with huge numbers as it means that you spend years just doing slightly harder arithmetic problems when the kids could move on to higher level math with the aid of a calculator when necessary.”

Bingo. I spent a year learning to add, and subtract without borrowing, another year learning borrowing and multiplication up to 10*10, and the next three (up to 5th grade in the US system) on multiplication above 100 and long division. I don’t know why. I got the concept of all four operations inside two weeks, I would swear. For some reason though, possibly the novelty of school kids even having calculators in the late 80′s, it was important that I spend five years knowing how to do these should I ever be out of arms reach of a calculator. (My first, a TI-36, was solar, so I wasn’t buying that ‘what if your batteries are dead, what then, HUH?’ garbage from the teachers…)

Meanwhile, I’m pretty sure I could have been picking up some more advanced math, and I don’t

thinkI was particularly gifted such that this wasn’t the case with most of the class.## Nihilismus

March 13, 2014 at 1:42 am (UTC -4) Link to this comment

@21 M can help you with that.

And some of the proofs are more elegant and described more intuitively by replacing π with τ. Explaining how they relate to each other and how each can be derived geometrically or mathematically can also build on students’ understanding — but trying to replace π with τ might result in the same kind of outrage we are seeing over Common Core.

@33 & 35 Pierce R. Butler

Since the kids won’t learn cursive, when they attempt to mimic it for a signature, it will not only be illegible (like most people’s signatures), but it will be harder for a forger who knows actual cursive to forge the fake cursive.

## martinc

March 13, 2014 at 1:57 am (UTC -4) Link to this comment

All this purchase-related math assumes that you know how much things cost anyway. Due to North America’s stupid insistence on listing the price of everything

pre-tax instead of listing what it will actually cost you (i.e. the “price”), it is almost impossible to know what you are going to be charged at the counter, so most people just hand over a large enough bill* and ladle the great wad of pennies** they receive in return into their purse or pocket and hope it’s right. For the rest of the world, buying a chocolate bar pricemarked ‘$2.90′ is going to cost you – I’ll give you a drumroll for thinking time, though I’m sure the cleverer among you are already way ahead of me – $2.90.* American money. All the bills are exactly the same color. Why? And they only use two colors in the printing … is that to make it easier for forgers?

** Pennies. Don’t get me started on pennies. Just round the total price to the nearest 5c, fercrissake.

/rant

## Ichthyic

March 13, 2014 at 5:15 am (UTC -4) Link to this comment

this is EXACTLY correct.

this IS the way authoritarian leaning personalities work, and the right is overpopulated with authoritarian personalities.

an authoritarian would much rather have a trusted authority figure simply tell them what the formula or answer is, rather than working it out themselves.

this is real, people. 30% of human populations (on average) exhibit strong authoritarian personalities. We really do need to accept that, and deal with it properly.

## Ichthyic

March 13, 2014 at 5:18 am (UTC -4) Link to this comment

…which is why establishing some sort of rigid standard simply WILL NOT WORK.

if you want to teach logic, most of the kids will get it, but 30% simply will NOT. they should not be punished for that, as they do just fine often by rote memorization of formulas and facts.

it’s no wonder the right is afraid of this; something in them tells them their kids likely won’t be able to learn this way, and they are likely correct.

## democommie

March 13, 2014 at 9:07 am (UTC -4) Link to this comment

I look at comments like those @22 and they make me realize how seriously deficient my math skills are. I CANNOT follow the process laid out for Chiroptera at the end of the comment.

This has been explained to me, by two different psychologists as a math learning disability. It completely closes off most scientific or engineering disciplines, for me. Until I was told that it WASN’T because I was stupid or lazy, that was my default explanation from teachers and others.

@37:

As do I, Jaybee. I also tell them why I’m doing it. Most of them are actually curious about the process and I generally explain it with one word, “nuns” (I live in a pretty catholic city and it works).

Back when I was a hardware clerk/industrial supply sales engineer (the same job, no less) people got 10% off on most items (there were some “nets” that were not discounted) and 20,25,30 & 33-1/3 % discounts on various items or classes of items. We did not write receipts for small sales because it was time consuming and the receipts were not required for small sale returns. I would often have someone approach the counter with a handful of small items; some flat-head woodscrews, a Stanley screwdriver, 2 # of drywall screws, a qt of spackle and 50′ of #4 sash cord. I would ask them if they needed a receipt. When they said, “No.”, I would look at the items,. sort them in my head for pricing and discount, add the amounts plus tax and tell them it was, say, $31.17. They would often look at me with a, “WTF? how do I know that you’re not ripping me off?”. At that point I would grab a receipt pad, put the items on it, price them, extend for quantities, figure discounts and final prices and add everything up adding sales tax to the pre-tax total. I was never more than few cents off (and that generally in their favor). Most folks didn’t ask me to do that more than once or twice before they decided that I wasn’t trying to fuck them. I never gave much thought to how it happened. I can’t think in mathese.

## democommie

March 13, 2014 at 9:23 am (UTC -4) Link to this comment

The “$31.17″ figure by the way is because I was thinking about putting a gallon of wall paint (Alkyd enamel with oodles of “long” oils–’spensive–Kyanize Lustaquik for example). Otherwise the total would have been around $15.

Oh, my employer at that business (and friend for over 45 years) always used to tell me to mark stuff up so that he would get a 33% “Gross” on the sale. He would then tell his customers that he was marking said item up, “1/3″. I explained the concept of mark up/margin to him until I was blue in the face. He was just too damned dense to understand.

He lives in several different houses, commutes between them by flying or driving one of his several Beemers and gets by as well as anyone can with only about 10% liquidity on their $M’s. He seems able to live with his lack of understanding of some math.

Oh, yeah, one more quick story.

I had an engineer tell me that he needed five 80# bags of Sakrete to pour a pad. I asked him how big and how thick. He said 6′ x 9′ by 4″ were the dimensions. I told him that he was going to need 30 bags of Sakrete. He laughed at me, took 5 bags and left. He came back two hours later for 10 more bags, and about three hours after that for 15 more bags. He was mad at me, apparently because I had caused the problem by telling the truth. Did I mention that he was WAAAAAAAAAAAAAAAAAAAAAAAAAY conservative, back in the Nixon era? He was a nice guy, really, but I’m guessing that he’s a teabagger, today.

## anne mariehovgaard

March 13, 2014 at 10:05 am (UTC -4) Link to this comment

I usually don’t use either of those methods (or any other method described here), I do it visually (possibly because I didn’t learn this in school but at home, using legos and other toys): 10 (100/1000/10000…) is a

whole(circle, square, whatever), so I add or subtract as needed depending on which is closer, to make as many of those as I need. Then I count them, subtracting or adding the “leftovers” to get the answer. Not sure if that makes sense to anyone else, but it’s very obvious and easy when you “see” it. For the example, this would be: 32-12 => 30-10=20, +2 -2 cancel eachother out. Or rather, “3 of those, leave the 2 small bits for now, push 1 to the side, push 2 small bits to the side, count what’s left”## Dane Hoffman

March 31, 2014 at 10:29 pm (UTC -4) Link to this comment

I’ve been an Atheist since I was about 10 (I’m 14 now), and I respect Hemant Mehta, but he might want to look into Common Core a little more.

I oppose the idea that one political party has to stand by its own set of rules, and immediately reject the others’. Which is why I never associate with one political party over another, because they both have their good ideas and their awful ideas. And I think that teachers everywhere in the U.S. have been scammed by someone who pretends to know what they’re talking about and sells a curriculum to schools. Just a few minutes of research will tell you that students that use Common Core are soiling themselves and vomiting during tests at a rate that has caused quite a number of public school principals to become genuinely concerned. I don’t blame those children.

A division problem (that students take home for homework) could be divided simply (90/18=5), but if the students don’t go off on a 108 step escapade to show how they got the answer, they get the whole question wrong. That’s not just taking an unnecessary detour (just like the subtraction problem on the photo), that’s flying to Mexico, swimming to Japan, taking a boat back to Canada and running all the way back to my house just to get to the coffee table that’s sitting 5 feet in front of me.

Common core homework is generally extremely convoluted and difficult for a child’s mind to comprehend. It’s often misprinted, in one case asking students to find the fraction of the geometric shape that is shaded in, however none of the shapes had been shaded in at all. They give VERY few (or no) instructions on a ridiculous amount of their homework, and children often need their parents to do their homework for them because the caliber and complexity of the homework that even kindergartners are given is too much to bear, only to find that the parent has absolutely no clue what to do either.

They’re edging away from a personalized and customized approach to teaching, to a one-size-fits-all, lazy central education curriculum. They’re ditching thought provoking answers that require a student to think about what they write down in favor of factual answers that just require a student to memorize a word.

“Everybody is a genius. But if you teach a fish on its ability to climb a tree, it will live its entire life thinking that it is stupid.” – A fake Albert Einstein quote based on the story “The Animal School” written by George Reavis.

## common core math - Page 9

March 24, 2014 at 3:16 pm (UTC -4) Link to this comment

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