Practise finding pairs of multiples of 5 that total 100. There are only about ten pairs and if possible they should be learnt.

You may have seen tables' grids: these are addition grids and work in just the same way, adding rather than multiplying.

Adding several numbers. A useful tip is to look for pairs of numbers that make 10 and do that part of the sum first.

Use knowledge of place value to add quickly.