A Mathematical Beginning

Today, my grade 5 son came to me with a subtraction problem 932-356 According to him, he has yet to learn how to subtract “big” numbers. He was quite confident in his ability to subtract 13 from 20 but faltered as soon as three digit numbers were presented. So I set the problem up for him (in the way that I learned to subtract “big”numbers) and I realized that I could not explain the “borrowing” thing in a meaningful way. And why ...