Concept very good but cutting corners by not having the numbers on all the sides
It would have been perfect and entertaining is all the sides of the cube had the numbers written on them instead of just one side. This is why it is not very useful as kids and adults get fed up of keep turning the cubes to look for the numbers.
I bought this for my grandson who is 4, I bought a little early but it is s great product. Like the fact that the answer is on the back. Good to test even an adults memory on time tables.