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 Author: questioner [ Thu Sep 13, 2012 4:18 am ] Post subject: GRE Number Theory Which of the following integers is/are the product of exactly two different prime numbers?21, 22, 23, 24, 25Credited Answer(s):21, 22The correct answers are 21 and 22. Let's factor each possible answer.Choice A: 21 = 3 × 7Choice B: 22 = 2 × 11.Choice C: 23 = prime number.Choice D: 24 = 2 × 2 × 3 × 3.Choice E: 25 = 5 × 5.Only the first two choices (21 and 22) are the product of exactly two different prime numbers.----------23 is also the product of the two following different prime numbers:23 and 1

 Author: Gennadiy [ Thu Sep 13, 2012 4:18 am ] Post subject: Re: GRE Number Theory Quote:23 is also the product of the two following different prime numbers:23 and 11 is NOT a prime number.

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