Carcass wrote:
If n is an integer and \(\frac{ 210}{n}\) is an integer, which of the following could be the value of n?
Indicate all such values.
A 6
B 12
C 14
D 35
E 42
This question is asking us to
find values of n that are divisors of 210A lot of integer property questions can be solved using prime factorization.
For questions involving divisibility, divisors, factors and multiples, we can say:
If k is a divisor of N, then k is "hiding" within the prime factorization of NConsider these examples:
3 is a divisor of 24, because 24 = (2)(2)(2)
(3), and we can clearly see the
3 hiding in the prime factorization.
Likewise,
5 is a divisor of 70 because 70 = (2)
(5)(7)
And
8 is a divisor of 112 because 112 = (2)
(2)(2)(2)(7)
And
15 is a divisor of 630 because 630 = (2)(3)
(3)(5)(7)
-----BACK TO THE QUESTION!---------------------
210 = (2)(3)(5)(7)A 6 =
(2)(3) 210 =
(2)(3)(5)(7)
So,
6 IS a divisor of 210B 12 =
(2)(2)(3)210 = (2)(3)(5)(7)
Since 12 is NOT hiding in the prime factorization of 210, 12 is NOT a divisor of 210
C 14 =
(2)(7) 210 =
(2)(3)(5)
(7)So,
14 IS a divisor of 210D 35 =
(5)(7)210 = (2)(3)
(5)(7)So,
35 IS a divisor of 210E 42 =
(2)(3)(7)210 =
(2)(3)(5)
(7)So,
42 IS a divisor of 210Answer: A, C, D, E