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Answer: Choice A) 45</h3>
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Explanation:
Since 300 is a multiple of some number, this means that mystery number is a factor of 300.
So for instance, she could have picked 60 since 60*5 = 300. Or she could have picked 50 because 50*6 = 300.
To find out if you have a factor or not, divide the 300 over each answer choice. If you get a whole number, then it is a factor.
- A) 300/45 = 6.67 approximately
- B) 300/50 = 6
- C) 300/60 = 5
- D) 300/75 = 4
Choices B through D lead to whole number results, which shows that the numbers 50, 60 and 75 are factors of 300. Flipping things around, this means that 300 is a multiple of 50, 60, and 75.
Only 45 is the one that isn't a factor of 300, which means that 300 is <u>not</u> a multiple of 45.
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Another way to see this is to list out the multiples of 45
- 45, 90, 135, 180, 225, 270, 315, 360, ...
and we don't land on 300. The closest we get is 315.
In contrast, let's list out the multiples of 50
- 50, 100, 150, 200, 250, 300, 350, 400, ...
The value 300 is in the list, allowing us to cross off choice B. Choices C and D are similar.
