Description: Sal subtracts 6798-3359 using regrouping. Created by Sal Khan. So let's see how far we can get with the subtraction. So immediately, when we go into the ones place, we're going to try to subtract a 9 from an 8. And to see what our options are here in terms of regrouping, I'm going to rewrite both of these numbers.*Teacher Advisor is 100% free.