Problem #12


Let S(n) denote the sum of the (base 10) digits of n. Show that for any positive integer m there is an n such that

m = S(n2)/S(n).

For example, when m = 4, n = 13 works since 132 = 169 and S(169)/S(13) = 16/4 = 4.

The solution will be posted shortly.

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