Maths Olympiad Prep

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Algebra Difficulty 1.1 Junior Find the answer Canada

Which of the following numbers is closest to 3.4-3.4?

Pick one

Solution

On a number line, 3.4-3.4 is
between 4-4 and 3-3.

This means that 3.4-3.4 is closer to
4-4 and 3-3 than to any of 0, 3 or 4, and so the
answer must be 4-4 or 3-3.

If we start at 3-3 and move in the
negative direction (that is, to the left), we reach 3.4-3.4 after moving 0.40.4 units.

It then takes an additional 0.6 units to move in the negative direction
from 3.4-3.4 to 4-4.

Therefore, 3.4-3.4 is closer to 3-3 than to 4-4, and so the answer is (B) or 3-3.

Alternatively, when comparing 3-3,
4-4 and 3.4-3.4, we could note that 3.4-3.4 is between 3.5-3.5 and 3-3 and so is closer to 3-3:

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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.