Tregolis ( math with cuisenaire rods )

A simple math game inspired by the famous block game.

Are falling blocks (cuisenaire rods) , numbered from 1 to 9.
Your goal is to click on these in order to avoid accumulating one on the other.
However, for each of them you will have to give the right answer, the sum should always be 10.
If the answer is right the block will disappear.