When we are multiplying by a number ending in 5 we can double the number and halve the other number before multiplying (by a multiple of ten, making it easy).

Some people (especially those who still use feet and inches!!) think it is important to know how to multiply by 12. It?s easy ? just add 10 times the number to 2 times the number.

When multiplying 2-digit numbers by 1-digit in your head usually it is easier to start with the tens.

Multiplying three digit multiples of 100 is fairly easy, but there are some addition adjustments to make on some of these.