Using column subtraction When you use the column method to subtract two numbers, the larger number goes above the smaller number. You then subtract digits from each column, starting with the ones.

Subtraction with exchange When you use the column method to subtract two numbers, the larger number goes above the smaller number. You then subtract digits from each column, starting with the ones.

Ellis showed a subtraction problem, performed both using the traditional regrouping, or borrow-and-carry, algorithm and using an example from the common core. Here’s a screenshot of the two methods.