Question 28
Vadim has a square piece of paper divided into nine cells. He folds the paper as shown, overlapping horizontally and then vertically so that the grey square ends on top. Vadim wants to write the numbers from 1 to 9 into the cells so that, once the paper is folded, the numbers are in increasing order with number 1 on the top layer. What numbers should he write instead of a, b and c?
