Hi, Dave. I just stumbled across your post of August 17 about visualization and mental math. I'm a college math teacher; I teach algebra and calculus.

I think you have a wonderful mathematical mind! You're just confusing "math" with "arithmetic", a common mistake. Doing arithmetic quickly requires memorizing number facts like the multiplication table. There are lots of people who are very successful in algebra and calculus who never do memorize those number facts. (My son is one of them.) The visualization you describe clearly shows me that you really understand what's going on with the numbers, even if you don't have the facts memorized.

I use a lot of visual images in my teaching, and I find that I use lots of little tricks like the one you describe (the quarters on the pop cans; that was great!) When I multiply by fifteen, I always think of a clock face, and quarter hours. When I multiply by 25, I always think of quarters, which makes me think of dividing by 4 instead of multiplying by 25. (Dividing by 4 is relatively easy: you take half and then half again.) I remember 4x13=52 by thinking of a deck of cards.

Please don't let yourself believe that you "suck" at math. Math is more than just crunching numbers. If you need help with number crunching, Chisanbop might be great for you. God gave you fingers for a reason. :-) Or just use a calculator. But I think you really do have a mathematical mind. A true mathematician always wants to know why something works, and isn't satisfied just memorizing something. When I was in graduate school, the math classes I took had almost no numbers in them. (We used to joke that the only numbers were at the bottom of the page.) It was all about why things work the way they do.

Good luck!

Karen

> > And addition
> > and subtraction don't require thought, as far
> > as I can tell.
>
> Ah, see, this is completely a foreign concept to me. Like spelling the word foregien.
>
> I do addition and subtraction on my fingers. Always have. I don't know how to do it otherwise. Even if I try to do it visually in my head, like say for instance seeing 5 dots then seeing 3 dots, I STILL have to say, "Ok, 5 dots, and 3 dots. So 5, 6, 7, 8 dots!" I count them. I have to.
>
> Certain types of addition I have memorized. I used to play cribbage a lot, so I know that 10 and 5, 9 and 6, and 8 and 7 all add up to 15. If you've ever played cribbage you know why I memorized those. But for most things, it's counting on my fingers time.
>
> I don't get it. I never have. I still get laughed at when I have to do any simple math and someone catches me counting on my fingers. But I can't seem to do it any other way.
>
> -- Dave