All 25 boxes in the square below contain whole numbers, but more than half of them are hidden from view.
The five numbers in each row add up to the same total, and the five numbers in each column also add up
to that same total.
Can you figure out what number belongs in the square containing the question mark?
Solution to the Problem:
The number 5 belongs in the box with a question mark.
From the information given in the problem, the two rows containing the shaded boxes must add up to the same total as the two columns containing the shaded boxes. Since the shaded boxes are part of both totals, they can be disregarded to write the equation
14 + 2 + 20 + 10 + 23 + 11 = 25 + 16 + 12 + 13 + 9 + ?
Therefore, 80 = 75 + ?
Hence, ? = 5.
Correctly solved by:
| 1. Michael Reilly | Silver Spring, Maryland |
| 2. James Alarie | Flint, Michigan |