In a tower, every brick is the sum of the two bricks right below it.
At the top you see the blocks. Exactly these numbers go into the bottom row, each of them once.
Only their order is open. Try them out until the given bricks match.
Example
For parents
What does this exercise practice?
The number tower practices systematic trial and error. The child does not just add, but tests an arrangement, discards it and uses the result to pick the next one. Along the way it becomes visible that the middle block counts twice towards the top.
Common pitfalls
Each block may be used only once. Using a number twice often produces a matching top, but then the supply of blocks no longer fits.
How to practice at home
Put three toy blocks with numbers on them in a row and say the sums above them out loud. Then swap the blocks. Which order makes the top the biggest?