Maths Olympiad Prep

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Problem 151

Combinatorics Difficulty 1.2 Find the answer CEMC Cayley · Canada · 2023

The number 2023 is written on one side of a classroom
window using the style of numbers shown.

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If you were to stand on the other side of the window, how would the
number appear?

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A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

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Official solution

When looking at [[IMAGE0]] through a window from behind, the digits appear as mirror images
and in reverse order, and so appear as
[[IMAGE1]] .

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