Don’t panic, we just need to answer the calculation to open the door. Something tells me that was not the correct answer. But 12 minus nine is three, three divided by three is one, and one plus 12 is ...

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, ...