This activity is about working out the difference of two square numbers.
We use the fact that a2 - b2 factorises to (a + b) (a - b)
Work out the difference of these two squares:
4852 - 4832
We need to work out (485 + 483) (485 - 483)
Notice that the first bracket equals 968 and that the second bracket equals 2
So this is 968 x 2 = 1,936
Being able to find the difference between two squares in this way can sometimes make it possible to do the calculation without the use of a calculator!
Let's have a go at some questions.