All about
flooble

fun stuff

Get a free chatterbox

Free JavaScript

Avatars
perplexus
dot
info
Home
>
Just Math
The Last Two Digits (
Posted on 20130904
)
What are the last two digits of (1+5^(2n+1))/6?
Note that n is assumed to be any positive integer.
No Solution Yet
Submitted by
Danish Ahmed Khan
Rating:
4.0000
(1 votes)
Comments: (
Back to comment list
 You must be logged in to post comments.
)
another way
 Comment 2 of 3 
Factor the numerator as (1+5)(15+...+5^2n) and note that positive powers ending in 25 are offset by negatives. You're left with (15+25)=21 since the (1+5) factor cancels.
Posted by
xdog
on 20130904 12:22:43
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 (5)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On
Chatterbox:
blackjack
flooble's webmaster puzzle
Copyright © 2002  2018 by
Animus Pactum Consulting
. All rights reserved.
Privacy Information