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Prime Number Problem

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Prime Number Problem

by Wheeoh » Tue Feb 23, 2010 6:53 pm
Hello,

I can figure out this problem, but not in less than 2 minutes. Any thoughts on how to solve this problem quickly? Thanks!

The product of all prime numbers less than 29 is approximately equal to which of the following?

A. 2 x 10^4
B. 2 x 10^6
C. 2 x 10^8
D. 2 x 10^9
E. 2 x 10^10
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by thephoenix » Tue Feb 23, 2010 8:23 pm
Wheeoh wrote:Hello,

I can figure out this problem, but not in less than 2 minutes. Any thoughts on how to solve this problem quickly? Thanks!

The product of all prime numbers less than 29 is approximately equal to which of the following?

A. 2 x 10^4
B. 2 x 10^6
C. 2 x 10^8
D. 2 x 10^9
E. 2 x 10^10
imo b
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by ajith » Tue Feb 23, 2010 10:46 pm
Wheeoh wrote:Hello,

I can figure out this problem, but not in less than 2 minutes. Any thoughts on how to solve this problem quickly? Thanks!

The product of all prime numbers less than 29 is approximately equal to which of the following?

A. 2 x 10^4
B. 2 x 10^6
C. 2 x 10^8
D. 2 x 10^9
E. 2 x 10^10
We are talking about 2*3*5*7*11*13*17*19*23

11*13*7 = 1001
17*3*23 close to 1100
19*5 = 95

so this will be close to 2*10^3*10^3*10^2 = 2*10^8
Always borrow money from a pessimist, he doesn't expect to be paid back.
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