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Algebra Difficulty 1.4 Junior Find the answer Canada

The number represented by $\Box$ so that $\frac 12+\frac 14=\frac{\Box}{12}$ is

Pick one

Solution

Using the digits $4,7$ and 9 without repeating any digit in a given number, the following 3-digit whole numbers can be formed: $479, 497, 749, 794, 947,$ and 974.
There are exactly 6 different 3-digit whole numbers that can be formed in the manner described.

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