25
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25 is a square number, i.e. 52 = 25
All powers of 25 end in the digits 25
25 is the sum of two squares 9 and 16, i.e. 32 + 42 = 52 = 25
25 is the sum of the first 5 odd numbers, i.e. 1 + 3 + 5 + 7 + 9 = 25
All squares, including 25, are the sum of two triangle numbers, i.e. 10 + 15 = 25 |