Counting n with a Units-Digit Condition

★ 7/10number theory Counting Modular Arithmetic

Problem

Find the number of positive integers $n\leqslant 2015$ such that the units digit of $1^n+2^n+3^n+4^n$ is $0$ .

Answer

Solution

Difficulty	7/10
Topics	number theory, Counting, Modular Arithmetic

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