Why do this problem?

This problem is tricky to do but can form an interesting challenge to those who need it. It requires much addition & subtraction as well as the making and testing hypotheses.

Key questions

Have you tried adding the diagonals?

Can you get a clue from the way numbers are selected if you look carefully at the way this is forced to happen?

Does it help to look at the diagram in the hint section?

Possible extension

Learners could make their own puzzle matrices.

Possible support

Suggest doing a easier problem such as Shapes on the playground.