37 rounds to 40, and 52-40 is 12, then I add back in the 3 that took 37 to 40, for a total of 15.

I do this too. My mommy taught me in seventh grade math class.

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Toddson--those boots are totally adorable.

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Cute boots! I like the silly. They look warm, too, which is very appealing this morning.

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Cute boots! I like the silly. They look warm, too, which is very appealing this morning

Seriously! My toes are little icicles (because I didn't have the sense not to wear sandals today).

Hah! I'd totally forgotten I'd gotten RIDIC x INFINITY purple boots for winter this year until I looked in my closet the other day.

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Random question: What sort of process do you use for doing subtraction in your head? Like, if I had to figure out 52-37, I would think 52-30=22, 22-7=15, but I've been told that this seems strange to other people. I don't think I was ever taught that method -- it's just what seems natural to my brain. So do other people do it that way, or some other way, or think through the regular written process, with "borrow a ten, 2 becomes 12, 5 becomes 4" and so on

Depending on the numbers, I'd either go with 52-30 = 22; 22-7 = 15 or else round the 37 up to be 40, as Tep said.

We actively teach both these (and various other) strategies to kids in primary school, with a lot of emphasis on the fact that different people will favour different strategies, and that so long as your method is a sound one, it's all cool - that there isn't One True Way of working out a problem. We do a lot of setting them problems and then focusing on HOW they got the answer, rather than what the answer was. it helps both in terms of picking up handy ways of doing things from other kids, and also in terms of identifying where you're getting mixed up, if you've got the wrong answer.

I mention this only because I don't think that I was taught in quite this way myself - I have more of an impression of there being impenetrable methods and little encouragement of discussion or risk-taking. (But my memory isn't neccesarily to be trusted, and is most subjective.)

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Message for Erin:

I am sad to report that I will not be attending the NCTE Convention. School said nuh-uh, too much moola.

I am comforted, however, by the fact that I have been approved to attend The Key West Literary Seminar! I'm going with three of my colleagues from school, so it should be a blast. Plus, hanging out with famous writers! Very cool.

I'm bummed I won't see you, though.

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Brrr. Morning air in bedroom is just cool enough to encourage staying in warm bed, and thus making me late for work. Ugg. gronkies. Blah.

jiggles pornpoms once again

That helps ;)

Random question: What sort of process do you use for doing subtraction in your head?

It depends on the numbers, and if they are both easy sets, or not (easy number being a 5 or a 10), if not then much like StephL response of:

37 rounds to 40, and 52-40 is 12, then I add back in the 3 that took 37 to 40, for a total of 15.

Same works for ÷ and x math too. Break it down into something simpler, then make up for the change.

(and to those on my LJ, apparently at 2am, the joke seems funnier, so I just deleted it. Sorry)

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It occurs to me that I will also do subtraction in three pieces. Like if I need to figure out how old I am (no, I can't just remember), I'd note that 2000-1970 is 30, add a one because I was born in 1969, and add 7 because this is 2007, so I'm 38. Then I have to check what month it is, of course. And be surprised because I'm never the age I think I am - I tend to think of myself as 39, lately, I don't know why.

Anyway, I use this whenever the difference spans some convenient threshold - 52-37 doesn't, to me, but 65-42 would, and anything that's a hundred something minus a two digit number would likely get this treatment.

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52-37

I read all the way here thinking I do it like the most of you guys but then I actually did the math and realized I change it into an addition problem. My goal is 52, 37 + 10 is 47, plus 5 is 15. Also I use Chisanbop to keep track of where I'm at.

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