Ok. People. I'm trying to pay my bills online. I do this because I don't want to talk to a person. So, why have 2 of the 3 sites I've visited to pay my bills have been down for scheduled maintenance. Don't you want my money?!

Gronk.

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?

(Got onto this train of thought in sign class last night, when we were doing a bunch of exercises in learning the signs for numbers and the signs for "give," "take," and a few other words like that, where we'd watch someone sign something like, "Sally has 50 cents. Bob has 45 cents. Sally give 15 cents to Bob. Jane takes 30 cents from Bob. How much money does Bob have?" and, even though I'm generally considered pretty bad at mental arithmetic, I was the first one to have the answer to every one of them. So I got wondering about how other people process this.)

Brains are neat.

I think I do, 50 - 30 is 20, 7>2 so 10, 12 - 7 is 5, 15. Which may not be the best way to do it, since I've been known to skip the "7>2 so subtract 10" step, but it's what I do.

Hil, you'd probably be interested in this LJ entry (actually, both these entries), which poses almost the exact same question:

[link] [link]

She's got a tag for other math-related entries and math teacher stuff.

Hil, I think I do it the way you do it. I also add the same way - tens first then the ones.

Thanks Dana. That's really interesting.

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?

I would do 52-7=45 and 45-30=15. No one taught me it either.

{{Suzi}} Glad you got a validating e-mail, and glad that there's a job with more money that you're qualified for, even if it is in SJ.

I subtract in my head much like you do, Hil, but it is laborious for me. I can do it but my fingers itch for a pencil the whole tinme and I don't really trust the answer unless I run through it a couple more times to be sure. Or count on my fingers. I certainly was never taight to do math in my head, though I did get some tips on approximations at some point.

I did have a college professor who taught tricks for multiplying largish numbers in your head, but I did not pay attention. It was a parlor trick sort of thing.

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

I count by tens from the lower number to the higher number, then figure the difference of the ones column. I can't visualize the numbers well enough to work it as a problem.

What sort of process do you use for doing subtraction in your head? Like, if I had to figure out 52-37

Hil, I would do it kind of like you, only not entirely.

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.