Challenge Level

One of the following is the largest of nine consecutive positive integers whose sum is a perfect square. Which one is it?

A. 118

B. 128

C. 138

D. 148

E. 158

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

This problem is taken from the UKMT Mathematical Challenges.

You can find more short problems, arranged by curriculum topic, in our short problems collection.