MathDB
Numbers placed in a 7x7 array

Source: Baltic Way 2001

November 17, 2010
combinatorics proposedcombinatorics

Problem Statement

The numbers 1,2,…491, 2, \ldots 49 are placed in a 7×77\times 7 array, and the sum of the numbers in each row and in each column is computed. Some of these 1414 sums are odd while others are even. Let AA denote the sum of all the odd sums and BB the sum of all even sums. Is it possible that the numbers were placed in the array in such a way that A=BA = B?
Back to ProblemsView on AoPS