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Last three digits (Posted on 2011-10-19) Difficulty: 3 of 5
N is the product of all the prime numbers less than 100.

Determine the last three digits of N.

*** For an extra challenge, solve this puzzle without the aid of a computer program.

No Solution Yet Submitted by K Sengupta    
Rating: 3.0000 (2 votes)

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Solution A child of 5 could do it.. | Comment 2 of 9 |

Child of 5: Daddy, I must solve this problem without the aid of a computer program!
Father: A002110 in Sloane contains a list. It's the entry corresponding to the largest prime less than 100. 
Child of 5(Much later): Daddy, which number is the largest prime less than 100? 
Father: Never mind, try A034386 in Sloane, which has a list of the primorials n# = product of primes <= n. It's the one with "100'next to it. 
Child of 5(Reading): So the number is 100 2305567963945518424753102147331756070 and the last 3 digits are 070.  

Father: And you did it all without a computer program! My son, you are the new Newton.

  Posted by broll on 2011-10-19 12:02:16
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