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

Home > Just Math
Lucas Digits Look (Posted on 2016-11-07) Difficulty: 3 of 5
L(N) denotes the Nth Lucas Number.

Find the first three digits of L(2016)

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Indirect computation | Comment 2 of 21 |
http://mathworld.wolfram.com/LucasNumber.html
gives a nifty formula
L_n=[phi^n] 

for n>=2 where phi is the golden ratio and [x] denotes the nearest integer function.

Raising the golden ratio to the 2106 power is too large for my calculator, but its common logarithm isn't.

2016log(phi)=421.3190827

Raising 10 to this power allows us to write in scientific notation:

2.084888069x10^421

So the answer is 208


Edited on November 7, 2016, 9:28 am
  Posted by Jer on 2016-11-07 09:25:13

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 (9)
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