Rounding - addition

Rounding is a method for mental addition which is useful in many different situations.

Imagine you are in a shop and you have to quickly work out an amount.

£3.70 + £1.00 = £4.70. Taking away 10p gives £4.60

Have a look at how this addition sum can be solved with rounding:
      75 + 19

First, round the 19 up to 20 and work out the sum:
      75 + 20 = 95

As 20 is 1 more than 19, you then need to subtract 1 from the total.
      95 - 1 = 94

Then you can see that:
      75 + 19 = 94

Further reading.
These tables have some more information to help you with addition by rounding.

The first shows methods and examples for adding a number between 11 and 14 to another number.

This table shows methods and examples for adding a number between 15 and 19 to another number.