2 Subtracting in your head
To subtract one number from another without using a calculator you need to know basic subtractions up to 20. This means that you need to know, off by heart, what result you get if you subtract any number up to 10 from any bigger number up to 20. For example you have to remember that 14 minus 6 is 8, or 9 minus 5 is 4, and so on.
If you are confident that you know the basic subtractions up to 20, carry on with the rest of this course. If you are unsure, or would like some practice to help you remember them, then go now to Section 9 Subtracting small numbers by following the link on the left. Then return here to continue.