SAT Math Multiple Choice Practice Question 537: Answer and Explanation

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Question: 537

15. If the remainder when x is divided by 5 equals the remainder when x is divided by 4, then x could be any of the following EXCEPT

A. 20
B. 21
C. 22
D. 23
E. 24

Correct Answer: E

Explanation:

E One of the safest ways to solve this problem is by Plugging In The Answers. While you normally start with C, you don't want to forget that this is an EXCEPT question, so let's just start with A and go straight through to E. Assume x = 20. Is the remainder when 20 is divided by 5 the same as the remainder when 20 is divided by 4? Sure, the remainder is 0 in each case. So you can cross off A. (This is an EXCEPT question, don't forget!) How about B? If x = 21, is the remainder the same? Yes, the remainder is 1 when 21 is divided by 4 and when it is divided by 5. How about C? If x = 22, the remainder is 2 when divided by 4 and when divided by 5. How about D? If x = 23, then the remainder is 3 when divided by 4 and when divided by 5. If x = 24, however, the remainder when 24 is divided by 4 is 0, while the remainder when 24 is divided by 5 is 4. Therefore, E is our answer.

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