perplexus.info :: Numbers : Simple composite number

Home > Numbers

Simple composite number (Posted on 2023-07-26)

Show that the number 9999999+1999000 is composite.

No Solution Yet Submitted by Danish Ahmed Khan

No Rating

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

Solution

| Comment 2 of 3 |

This is the reverse order of how I worked this out.

But going in this direction would be a way of solving without having already factored:

9999999+1999000 = 11,998,999

11,998,999 = 11,999,000 - 1

11,999,000 - 1 = 12,000,000 - 1000 - 1

12,000,000 - 1000 - 1 = (3000 - 1)(4000 + 1)

(3000 - 1)(4000 + 1) = 2,999 * 4,001

so, composite

Posted by Larry on 2023-07-26 08:46:51

Please log in:

Forums (2)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (4)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info