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A “trio-prime” is any number made up of three factors, not [#permalink]
22 Oct 2017, 06:16

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Question Stats:

66% (01:14) correct
33% (00:29) wrong based on 6 sessions

A “trio-prime” is any number made up of three factors, not including itself and 1, that are consecutive primes. How many “trio-primes” are less than 1,000?

Re: A “trio-prime” is any number made up of three factors, not [#permalink]
22 Oct 2017, 09:21

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We can start listing the triplets of consecutive prime numbers we need to analyze, i.e. 2*3*5, 3*5*7, 5*7*11, 7*11*13, ... We should start from the highest in order to have an idea of where we are with respect to 1000. 7*11*13 = 1001, thus we know that the triplets before are those of interest, i.e. 2*3*5, 3*5*7 and 5*7*11. Thus, answer is 3 (B)

Re: A “trio-prime” is any number made up of three factors, not [#permalink]
11 May 2018, 07:06

IlCreatore wrote:

We can start listing the triplets of consecutive prime numbers we need to analyze, i.e. 2*3*5, 3*5*7, 5*7*11, 7*11*13, ... We should start from the highest in order to have an idea of where we are with respect to 1000. 7*11*13 = 1001, thus we know that the triplets before are those of interest, i.e. 2*3*5, 3*5*7 and 5*7*11. Thus, answer is 3 (B)

how can we be sure that there are no other TRIO PRIME no others other than 3?

greprepclubot

Re: A “trio-prime” is any number made up of three factors, not
[#permalink]
11 May 2018, 07:06