Which of the following integers is NOT a divisor...

[shawns119]

Which of the following integers is NOT a divisor of x if x = (21)(37) – (112)?
7
11
15
17
35

I saw this question in a recent diag and after trying to figure this one out for about 2 minutes I decided to guess and move on. After the exam I read the explanation given by Manhattan Prep but it seems like a long and arduous way of solving it. Is their a shortcut you would recommend to solving this problem?

[RonPurewal]

these numbers aren't that big, so, i would just do the arithmetic.
i'm not that fast at pen-and-paper arithmetic, but, even so, it's not like this is going to take some horrendously long time.

that said, 2 things...

1/
are you sure you've copied the problem correctly?
...because (21·37) – 112 = 665
and only two of those numbers (7 and 35) go evenly into 665. the other three (11, 15, and 17) don't.

so, your transcription of this problem actually has 3 different "correct" answers.

and...

2/
if you're going to refer to an answer key, please post the answer key here.

thanks.