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South African Mathematics Olympiad

Number theory Difficulty 3.7 AMC 10/12 Find the answer South Africa

If 12x\frac{12}{x} is a natural number and xx is a natural number, how many possible values are there for xx?

Pick one

Solution

xx must be a divisor of 1212, and the possibilities are 11, 22, 33, 44, 66, 1212, which is 66 in all.

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Source: MathNet, licensed CC-BY-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.