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Problem 259

Number theory Difficulty 2.2 Multiple choice CEMC Fermat · Canada · 2025

The current calendar year, 20252025, is a perfect square. In nn years from 2025, the calendar year will
again be a perfect square. The smallest possible value of nn is

Pick one

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Official solutions — 2

Solution 1

Since 2025=45\sqrt{2025}=45, the
next largest perfect square greater than 2025 is 462=211646^2=2116.

Thus, the smallest possible value of nn is 21162025=912116-2025=91.

Solution 2

Since 2025=45\sqrt{2025}=45, the
next largest perfect square greater than 2025 is 462=211646^2=2116.

Thus, the smallest possible value of nn is 21162025=912116-2025=91.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.