There are different methods for addition and subtraction. You may have used column addition and subtraction before but sometimes you can solve additions and subtractions using a mental method.

Rounding numbers to the nearest 1, 10 or 100 can help with lots of mental maths problems. To add 9 to another number, add 10 and then subtract 1: 36 + 9 = 36 + 10 - 1 = 45 To add 18 to another ...