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Project Euler - Problem 20

Aashu Aggarwal
Greenhorn

Joined: Aug 01, 2012
Posts: 4
Problem statement -

n! means n (n 1) ... 3 2 1

For example, 10! = 10 9 ... 3 2 1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.

Find the sum of the digits in the number 100!


I am trying to solve it but 100! is big even for long. I thought i can try to break the factorial in parts and then solve it but still in end i have to multiply all the results which overshoot the long.

Looking for some guidance.

Thanks,
Aashu
fred rosenberger
lowercase baba
Bartender

Joined: Oct 02, 2003
Posts: 11326
    
  16

Check the java API for something that might let you work with a Big Integer...


There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Aashu Aggarwal
Greenhorn

Joined: Aug 01, 2012
Posts: 4
fred rosenberger wrote:Check the java API for something that might let you work with a Big Integer...


Thanks Fred. That worked perfectly :-)
 
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subject: Project Euler - Problem 20