View Single Post
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)