A Grid of Sums: Lower Secondary Mathematics Competition Question

The diagram shows a row of five squares above a row of four circles. The number in each circle is generated by adding the numbers in the two squares immediately above it.

Using only the single-digit numbers 1 to 9, complete the grid so that every number is used once and every circle is the sum of the two squares above it. The diagram has the number 6 already inserted.

This question requires a bit of logic so that you can go through all the possible permutations in a systematic and quick way.

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