The array can be shown as 5 groups of 3 showing that 5 x 3 = 15. Or it could be shown as 3 groups of 5 showing that 3 x 5 = 15. This demonstrates that multiplication is commutative. Image caption, ...

Knowledge of converting numbers into and from standard form will be useful before looking at calculations with standard index form. Back to top How to add and subtract numbers in standard form, with ...