In the last article in this series on Mental Arithmetic we considered the problem of adding double-digit numbers.

The scope of mental arithmetic is now extended this to the topic of “number bonds” – which are the various ways in which a number can be divided up into two parts which then can be added together to get back to the number.

So number bonds are really the opposite of addition, since in addition we add two numbers to get a single number, and with number bonds we take a single number and then divide it into two smaller numbers.

This is an important part of early mathematics development and it is essential that this is imprinted into your brain as facts, so that you do not need to use a procedure for counting, since procedures take more brain work and slow you down.