All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Numbers
Center Digits (Posted on 2004-11-28) Difficulty: 3 of 5
A four digit number is squared to form an eight digit number. The center four digits of that square form the four digit number. Find all possible four digit numbers.

(If 'abcd' was the four digit number, then the eight digit number would look like 'wxabcdyz'.)

See The Solution Submitted by Brian Smith    
Rating: 2.2500 (4 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
the leading zeroes solutions | Comment 11 of 15 |

I'm surprised no one else bothered mentioning them but there are two further solutions with leading zeroes allowed (not technically 4 or 8 digit numbers but what the heck)

0100 = 00 0100 00

2500 = 06 2500 00

It should not be surprising there are so few.  There are only 10000 numbers to check and each has a 1/10000 chance of working if the digits were random.  This means we should expect only one solution.  The fact there are 4 without some kind of obvious pattern could be seen as kind of suprising.


  Posted by Jer on 2004-11-29 17:08:37
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (1)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2019 by Animus Pactum Consulting. All rights reserved. Privacy Information