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Re: How plenty of prime numbers between 1 and 100 are factors of 7,15<#permalink>09 Mar 2017, 16:01
How numerous prime numbers between 1 and 100 are components of 7,150 ?(A) One(B) Two(C) Three(D) Four(E) Five
Make prime factorization the 7,150 --> (7,150=2*5^2*11*13). So, 4 element numbers between 1 and also 100 (namely 2, 5, 11, and also 13) are components of 7,150.Answer: D.

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Bunuel,Do girlfriend have any fast top to recognize that 7,150 is divisible through 11 and also 13?The just silly mistake i made was to miss out on 11 and also 13 together prime factors of 7150.Thank you!
One that the questions above is how to recognize easily if a number is a lot of of 11 or not.Let (N) it is in an essence (a_m a_m-1 ... A_2 a_1 a_0) created in 10 base notation.Consider the difference in between (a_0 + a_2 + a_4 + ...), the amount of number at also numbered positions such as 0th, 2nd, 4th, ... And (a_1 + a_3 + a5 + ...), the sum of number at weird numbered positions together 1st, 3rd, 5th, ... .If (( a_0 + a_2 + a_4 + ... ) - ( a_1 + a_3 + a5 + ... )) is a lot of of 11, climate (N) need to be a lot of of 11.Here, in this question, we have ( 7 + 5 ) - ( 1 + 0 ) = 12 - 1 = 11, i beg your pardon is a multiple of 11.Thus 7150 should be a many of 11. For 143, ( 1 + 3 ) - 4 is 0, which is also a lot of of 11.Thus 143 is a lot of of 11.Are girlfriend curious around why?_________________
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Re: How plenty of prime numbers in between 1 and also 100 are determinants of 7,15<#permalink>25 Sep 2020, 04:03
7150 = 2 * 5 * 5 * 11 * 13 Prime numbers between 1 and also 100 are factors of 7,150 are: 2, 5, 11 and also 13. Toal Four.Answer D_________________
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Using prime factorization us get: 7,150 = (2)(5)(5)(11)(13)So, 4 prime numbers (2, 5, 11 and also 13) are factors of 7,150Answer: DCheers,BrentASIDE: because that anyone that feels the the correct answer must be E (since there are two 5"s in the element factorization that 7150), here"s why the correct answer is in reality DThe concern starts with "How countless prime numbers between 1 and also 100..."The prime numbers in between 1 and also 100 space 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97"....are determinants of 7,150"So, how numerous numbers from the collection 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 are factors of 7150?The prime factors of 7150 space underlined 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 are determinants of 7150There are four underlined primes_________________