2013 UMO Problems/Problem 3

Problem

Find all $x$ with $1 \le x \le 999$ such that the last three digits of $x^2$ are all equal to the same nonzero digit.

2013 UMO (Problems • Answer Key • Resources)
Preceded by Problem 2	Followed by Problem 4
1 • 2 • 3 • 4 • 5 • 6
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