The numbers 1 up to and including 8 must be put in the circles of the figure depicted below. However, numbers in neighboring circles must differ by more than 1. For example, circles connected to a circle with a 4 may not contain a 3 or a 5.

The question: How should the numbers be arranged in the circles of the net?

The answer: Click here!

Another question: The numbers 1 up to and including 9 must be put in the circles of the figure below, in such a way that the sum of the corners of each of the seven triangles (4 small ones and 3 large ones) is equal.

How should the numbers be put in the figure?

Another answer: Click here!

Yet another question: The large triangle below consists of three smaller triangles. The numbers 1 up to 10 should be placed in the fields of the large triangle, such that the sum of the numbers in every small triangle is 28.

How should the numbers be placed in the triangle?

Yet another answer: Click here!