The numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 must be put in the triangle depicted below, in such a way that the sums of the numbers on each side are equal.

The question: How should the numbers be arranged in the triangle?

The answer: Click here!

Another question: The numbers 1 up to 10 must be placed in the rectangle below.

The sum of the numbers on each side must be exactly 18. How can this be done?

Another answer: Click here!