Maths Olympiad Prep

Library / /12 of 183

, 2014

Number theory Difficulty 1.1 Junior Find the answer Canada

Which of the following numbers is closest to 100 on the number line?

Pick one

Solution

Solution 1

We place each of the five answers and 100 on a number line.

Of the five answers given, the two closest numbers to 100 are 98 and 103.
Since 98 is 2 units away from 100 and 103 is 3 units away from 100, then 98 is closest to 100.

[[IMAGE0]]

Solution 2

We calculate the positive difference between 100 and each of the five possible answers.
The number closest to 100 on the number line will produce the smallest of these positive differences.

Possible Answers
98
95
103
107
110

Positive Differences
10098=2100-98=2
10095=5100-95=5
103100=3103-100=3
107100=7107-100=7
110100=10110-100=10

Since the smallest positive difference is 2, then 98 is the closest to 100 on the number line.

Want a route through all this instead of an archive? The track puts 2,444 problems in a working order, from Junior Challenge level to the IMO shortlist.

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