Jane Street Interview Question: Last digit of 17^17... | Glassdoor

Interview Question

Intern Interview New York, NY

Last digit of 17^17

Answer

Interview Answer

3 Answers

5

You could use modular arithmetic if you want to be cute or just realize the pattern:

7, 9, 3, 1, ... --> 7.

Anonymous on Sep 28, 2016
3

euler's theorem if you want to be really cute

MT on Oct 12, 2016
0

17^2=(20-3)^2, so the last digit is going to be the last digit of 3^2 = 9

So the answer is 9

Just observe the complement of the last digit when squared on Jul 24, 2017

Add Answers or Comments

To comment on this, Sign In or Sign Up.