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

Home > Just Math
50 - Digit Number (Posted on 2003-11-15) Difficulty: 3 of 5
A number of 50 digits has all its digits equal to 1 except the 26th digit. If the number is divisible by 13, then find the digit in the 26th place.

See The Solution Submitted by Ravi Raja    
Rating: 3.0000 (7 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: A similar problem but perhaps a bit trickier | Comment 16 of 43 |
(In reply to A similar problem but perhaps a bit trickier by Kirk)

Since 10 is -1 mod 11, we can calculate the alternating sum of the digits and easily find that x=7. A similar method, employing the values of 10^n mod 13, can be used on the original problem, but it would be laborious due to the large number of digits.
  Posted by Richard on 2003-11-20 17:47:15

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 (14)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information