## Digital Square Sum

#### Problem

The digital sum of the year 2007 is 2 + 0 + 0 + 7 = 9, which is a square number.

How many years during the twenty-first century have a square digital sum?

Problem ID: 320 (14 Apr 2007) Difficulty: 1 Star

The digital sum of the year 2007 is 2 + 0 + 0 + 7 = 9, which is a square number.

How many years during the twenty-first century have a square digital sum?

Problem ID: 320 (14 Apr 2007) Difficulty: 1 Star