The Number Bond Generator creates a formula that when complete will result in the total shown.

A Number Bond is formed from a pair of numbers, the sum of which is equal to the target value. For example, '1 + 9' and '3 + 7' are both correct Number Bonds of 10.

The Number Bond Generator displays a Bond with the second value missing. For example, '1 + ?'. In this example, a child practising their Number Bonds should correctly respond with 9 as the missing value in the Bond.