Subtract tens then ones

The idea behind this strategy is break up the number you are subtracting into tens and ones.

For example, let's look at 45 minus 28. First, break up 28 into 20 (the tens) and 8 (the ones). Next, take away 20 from 45 to make 25. Then, take away 8 from 25 to get the answer 17.

This image shows 45 minus 28, with 20 and then 8 being taken away to make the answer easier to work out.

Use this strategy to work out 51 minus 12. First, break up 12 into 10 (the tens) and 2 (the ones). Next, take away the tens. Then take away the ones.

Did you get 39 for your answer?