2009 UNCO Math Contest II Problems/Problem 2

Problem

(a) Let $Q_n=1^n+2^n$ . For how many $n$ between $1$ and $100$ inclusive is $Q_n$ a multiple of $5$ ?

(b) For how many $n$ between $1$ and $100$ inclusive is $R_n=1^n+2^n+3^n+4^n$ a multiple of 5?

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2009 UNCO Math Contest II (Problems • Answer Key • Resources)
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