This time there?s a number square to help with subtraction. It?s interesting to see how children use the number square to help them.

Taking 15, 16, 17 or 18 from 2-digit numbers. The easiest way of doing this is by taking a whole ten and adjusting.

Use knowledge to subtract a single digit from a teen number quickly and efficiently. Rather than just counting up in ones, look for two steps, firstly to ten and then to the number.

A look at the inverse relationship between addition and subtraction.