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Norwegian
Norwegian is offline
#4
Feb23-12, 01:43 AM
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)[itex]\equiv[/itex]n (mod 10s-1) and Qs'(n)[itex]\equiv[/itex]n (mod 10s+1)