Maths: expanded subtraction

Today we looked at a written way of subtracting. We started by expanding the numbers into hundreds, tens and units. That made it easy to move numbers to other columns if we needed to. For example, in the tens column we had 10 (from the tens column in 911) subtract 80 (from the tens column). 10 is not enough to to subtract 80, so we have to take 100 from the hundreds column. 10 plus 100 is 110, and now only 800 is left in the hundreds column. It is easy to understand this method if you do it one step at a time. In fact, it works in the same way as the method of subtraction we all know already. This way, you can see how it works.