Why do this problem?

In this problem learners have to identify the mathematical features of the context and represent these features in graphical and algebraic forms. They will get practice in analysing and mathematical reasoning through using algebraic expressions and equations to find solutions. In order to check that they have found all possible solutions learners need to work systematically and check all possible cases.

Key questions

What is the sum of the whole numbers 1 to 9?

If the total in each circle is Xwhat can you say about the total of thenumbers that are in the intersections of the circles?