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

Home > Just Math

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)

Comments: ( Back to comment list | You must be logged in to post comments.)

Quick

| Comment 4 of 10 |

10^999=2^999x5^999, so it has (999+1)x(999+1) = 1000^2 divisors. Similarly, 10^998 has 999^2 divisors. The difference is 1000^2-999^2= (1000+999)(1000-999)= 1999.

Posted by Federico Kereki on 2006-05-18 10:00:58

Please log in:

Login:
Password:
Remember me:

Sign up! \| Forgot password

Search:

Search body:

Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (15)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info