I remember in early elementary being told I could not add 7 and 8 by taking 3 away from the 8 and adding it (the 3) to the 7 to get 10 then taking the resulting 5 (from 8-3) and adding it to the 10 to get 15. The teacher said it was "too complicated" and "probably wouldn't work when you get to higher math." So I shut up and just kept doing it in my head. A few years ago, I saw in one of DS's math books, *my* technique being taught under the heading "redistribution."
=
That is exactly the way I've always done addition, and I'm a mathematician now! I teach high school math! Good for you.
