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by shashank.ism » Wed Feb 10, 2010 11:10 pm
If P represents the product of the first 15 positive integers, then P is not a multiple of:

A) 99
B) 84
C) 72
D) 65
E) 57

Ans E
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by harsh.champ » Wed Feb 10, 2010 11:13 pm
shashank.ism wrote:If P represents the product of the first 15 positive integers, then P is not a multiple of:

A) 99
B) 84
C) 72
D) 65
E) 57

Ans E
If P represents the product of the first 15 integers, P would consist of the prime
numbers that are below 15.
2,3,5,7,11,13
Any value that has a prime higher than 13 would not be a value of P.
57 = 3, 19
19 is a prime greater than 13, so the answer is E.
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by ajith » Thu Feb 11, 2010 8:26 am
shashank.ism wrote:If P represents the product of the first 15 positive integers, then P is not a multiple of:

A) 99
B) 84
C) 72
D) 65
E) 57

Ans E
99 - 11*3^2
84 = 2^2*3*7
72 = 2^3*3^2
65= 13*5
57 = 19*3

15! = 2^11*3^6*5^3*7*11*13

Clearly 57 is not a factor
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by Scott@TargetTestPrep » Wed Mar 14, 2018 3:26 pm
shashank.ism wrote:If P represents the product of the first 15 positive integers, then P is not a multiple of:

A) 99
B) 84
C) 72
D) 65
E) 57
Let's look at the answer choices.

Since 99 = 9 x 11, both of which are included in the product of the first 15 integers, we see that P is a multiple of 99.

Similarly, since 84 = 42 x 2 = 21 x 4 = 7 x 3 x 4, we see that P is a multiple of 84.

Since 72 = 36 x 2 = 6 x 3 x 2 x 2 = 6 x 3 x 4, we see that P is a multiple of 72.

Since 65 = 5 x 13, we see that P is a multiple of 65.

Since 57 = 19 x 3, and since the product of the first 15 integers does not have a prime factor of 19, P cannot be a multiple of 57.

Answer: E

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