You can find the difference between two numbers in more than one way. You can count up from the smaller number to the larger number. Or, you can count back from the larger number to the smaller number ...

Join Ralph van Dijk and side-kick Matrix for more questions to consolidate mental maths skills. The focus today is adding and subtracting two-digit numbers.

The present paper describes the success, the methods (mental, informal written, standard algorithm) and the strategies of informal written arithmetic to be observed when 300 elementary students worked ...