Complete this quiz to ... You need to exchange a digit from the next column. Let's look at another subtraction. It's not possible to subtract 7 from 3, so exchange one ten from the tens column ...

Column subtraction ... you cannot subtract 3 tens from 2 tens. Once you have exchanged, you now have 12 tens take away 3 tens. 12 − 3 = 9 If you can subtract two 4-digit numbers from each ...