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 P: 144 Distribution of power congruence classes Can we perhaps decipher the question as follows: Let n and s be positive integers, let Qs(n) be the sum of the numbers formed by the digits of n in groups of s, starting from the right, and let Qs'(n) be the alternating such sum. Show that Qs(n)$\equiv$n (mod 10s-1) and Qs'(n)$\equiv$n (mod 10s+1)