April 21–April 27, 2009

Problem

A 5 by 5 square is divided into 25 unit squares. The numbers 1, 2, 3, 4, 5 are inserted into each of the unit squares in such a way that each row, each column, and each of the two main diagonals contains each of the five numbers exactly once. The sum of the four numbers immediately above the diagonal from top-left to bottom-right is called the value. What is the highest possible value?

Solution

here

List of solvers

Matt Inouye (undergrad); Koopa Koo (graduate); Gary Raymond (staff); Gaurav Chanda, Adam Welly, Mukund Tirumalai, Justin Shih, Lloyd Sakazaki, Mike Goodman (outside).

Justin Shih wins the prize!