Subtracting a single digit from a multiple of 1000. Then, moving on to subtracting two numbers just either side of the thousands boundary. They look tricky but are easy if you 'count on'.

A reminder that subtraction is the inverse of addition, and how this can be useful when working out mental calculations.

More adding and taking away 19, 29 etc. Easy if you know how!

Today we are going to look at a quick way that you can subtract numbers such as 999 from a 4-digit number.