perplexus.info :: Just Math : How many Integers?

How many Integers? (Posted on 2006-05-18)

Find the number of positive integers that divide (10)^999 but not (10)^998.

See The Solution Submitted by Ravi Raja

Rating: 3.0000 (1 votes)

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my way

| Comment 7 of 10 |

a number 2^m*5^n has (m+1)* (n+1) dividers

therefore 10^999 has 1000*1000=1000000 dividers

and 10^998 has 999*999= 1000000-2000+1 diividers

the difference is 2000-1= 1999

Posted by Ady TZIDON on 2006-05-20 15:07:26

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