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Problem 59

Number theory Difficulty 1.1 Multiple choice CEMC Gauss (Grade 7) · Canada · 2017

When two integers between 1 and 10 are multiplied, the result is 14. What is the sum of these two integers?

Pick one

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Official solution

There are only two different products of two positive integers whose result is 14.

These are 2×72\times7 and 1×141\times14.

Since the two integers must be between 1 and 10, then the product must be 2×72\times7.

The sum of these two integers is 2+7=92+7=9.

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