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If there are 664,579 prime numbers among the first 10 millio

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If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 26 Dec 2013, 09:02
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The Official Guide For GMAT® Quantitative Review, 2ND Edition

If there are 664,579 prime numbers among the first 10 million positive integers, approximately what percent of the first 10 million positive integers are prime numbers?

(A) 0.0066%
(B) 0.066%
(C) 0.66%
(D) 6.6%
(E) 66%

Problem Solving
Question: 10
Category: Arithmetic Percents
Page: 63
Difficulty: 550


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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 26 Dec 2013, 09:02
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SOLUTION

If there are 664,579 prime numbers among the first 10 million positive integers, approximately what percent of the first 10 million positive integers are prime numbers?

(A) 0.0066%
(B) 0.066%
(C) 0.66%
(D) 6.6%
(E) 66%

We need to find 664,579 is what percent of 10 million: \(\frac{664,579}{10,000,000}*100\approx{6.6%}\).

Answer: D.
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 26 Dec 2013, 21:00
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664579=x/100 * 10,000,000 = approx. 6.6%

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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 26 Dec 2013, 22:50
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664,579 = (x/100) * 10^7;
664, 579 = x * 10^5
=> x = 664, 579/10^5 = 6.64579 ~ 6.6%

Ans is (D).
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 27 Dec 2013, 01:37
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Writing\(664,579\) as \(0.66 * 10^6\)
Percentage of prime numbers in 10 million numbers \(= ( (0.66 * 10^6)/(10*10^6))* 100=6.6%\)

Answer: Option (D)
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 30 Dec 2013, 05:14
If there are 664,579 prime numbers among the first 10 million positive integers, approximately what percent of the first 10 million positive integers are prime numbers?

(A) 0.0066%
(B) 0.066%
(C) 0.66%
(D) 6.6%
(E) 66%

Sol: Given there 664 579 prime nos in first 10 million positive integers.So % will be

(0.664579*10^6/10 *10^6)*100 ------> 0.664579*10 and thus 6.6%
Ans D
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 02 Jan 2014, 05:56
10 million is 10 x 10^6 = 10^7

(664 579/10^7) x 10^2 = 6.6 %

Answer D
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 27 Aug 2014, 03:49
100,000 is 1 % of 10,000,000 hence 664,579 will be approx. 6.6% of 10,000,000.
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 31 Mar 2015, 06:56
664,579 / 10,000,000 *100 =x%

you can reduce the 10 million by 100, so that you only have 100,000 in the denominator. Now, bot the nominator and denominator have the same amount of digits and from this point you can ask yourself how much for e.g. 664/100 is. The solution is 6,64 or in this case 6,6%
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 31 Mar 2015, 11:24
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

If there are 664,579 prime numbers among the first 10 million positive integers, approximately what percent of the first 10 million positive integers are prime numbers?

(A) 0.0066%
(B) 0.066%
(C) 0.66%
(D) 6.6%
(E) 66%

Problem Solving
Question: 10
Category: Arithmetic Percents
Page: 63
Difficulty: 550


GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
1. Please provide your solutions to the questions;
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!


664579/10 million
= 664579/100,000,00
= 0.066
= 0.066 * 100%
= 6.6%

Hence option (D).

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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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New post 11 Nov 2015, 14:11
You can find interesting facts and puzzles about Prime Numbers and Magic Squares, Smith Numbers, and Arithmetic and Palindromic Primes on Glenn Westmore's blog.
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Re: If there are 664,579 prime numbers among the first 10 millio  [#permalink]

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Re: If there are 664,579 prime numbers among the first 10 millio &nbs [#permalink] 12 Nov 2017, 23:20
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