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If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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08 Mar 2013, 14:54
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If n = 2pq, where p and q are distinct prime numbers greater than 2, how many different positive even divisors does n have, including n ?(A) Two (B) Three (C) Four (D) Six (E) Eight
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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megafan wrote: If n = 2pq, where p and q are distinct prime numbers greater than 2, how many different positive even divisors does n have, including n ?
(A) Two (B) Three (C) Four (D) Six (E) Eight Answer  'C'  Four. For a number 2pq with primes p&q,there will be four even divisors  2,2*p,2*q,2*p*q



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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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Bunuel wrote: megafan wrote: If n = 2pq, where p and q are distinct prime numbers greater than 2, how many different positive even divisors does n have, including n ?
(A) Two (B) Three (C) Four (D) Six (E) Eight Since we cannot have two correct answers just pick two primes greater than 2, and see how many different positive even divisors will 2pq have. Say p = 3 and q = 5 > 2pq = 30> 30 has 4 even divisors: 2, 6, 10 and 30. Answer: C. Similar question to practice from OG: ifn2pqwherepandqaredistinctprimenumbersgreater148939.htmlAnother similar question: ifnisaprimenumbergreaterthan3whatistheremainder137869.htmlHope it helps. Total number of divisor of 2pq are (1+1)*(1+1)*(1+1)= 8 Total number of odd divisor of 2pq are (1+1)*(1+1)=4 Total number of even divisor of 2pq are = total divisor odd divisor=84=4 Hence c



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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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24 Sep 2014, 23:11
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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25 Sep 2014, 00:13
megafan wrote: If n = 2pq, where p and q are distinct prime numbers greater than 2, how many different positive even divisors does n have, including n ?
(A) Two (B) Three (C) Four (D) Six (E) Eight Because p and q are distinct prime number > 2, so p and q are ODD numbers 2pq = 2*odd*odd There are only four EVEN factors of n, including n (because n is even): 2 2*p 2*q 2*pq C is correct. Hope it helps.
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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06 Jan 2016, 19:31
Divisors are:
n, 2, 2p, 2q
C



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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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12 Jan 2017, 02:36
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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03 Apr 2017, 22:05
Even integer multiplied by any number whether odd/even will ALWAYS give even integer. For example, 2*3*3*3*3*3*3= 1458 Therefore in the above question there will be 4 even positive divisors of n. n=2*p*q p,q>2 2 is the only even prime number. Thus p and q are odd and will be counted under odd divisors. p*q (odd*odd) will also give odd. Thus the even divisors are: 2, 2p, 2q, and 2pq
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Re: If n = 2pq, where p and q are distinct prime numbers greater [#permalink]
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06 Apr 2017, 08:40
megafan wrote: If n = 2pq, where p and q are distinct prime numbers greater than 2, how many different positive even divisors does n have, including n ?
(A) Two (B) Three (C) Four (D) Six (E) Eight We can let p = 3 and q = 5. Thus, the product of 2pq is 2 x 3 x 5 = 30. The factors of 30 are: 1, 30, 2, 15, 3, 10, 5, 6 Since 30 has 4 even factors, n has 4 even factors. Alternatively, we can solve the problem algebraically. Keep in mind that p and q will be odd primes since they are greater than 2. The factors of n are: 1, 2pq, 2, pq, p, 2q, q, 2p We see that the even factors of n are 2pq, 2, 2q, and 2p, so there are 4 even factors. Answer: C
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