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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?
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