OU blog

Personal Blogs

Richard Walker

A Square Year

Visible to anyone in the world

Next year will be a square year. 2025 = 45 x 45, and this is the only square year in this century, because 44 x 44 = 1936 and 46 x 46 = 2116.

By the way, here is a neat trick for squaring numbers that end in a 5. Suppose the number is X5, where X is some series of digits that form a number in their own right. Work out X times X+1, then pop 25 on the end.

Take 135 as an example. 13x14 = 182, so we get 18225, which is indeed 135 squared.

Share post