Art of Problem Solving

2006 SMT/General Problems/Problem 12: Difference between revisions

Dividend (talk | contribs)
Created page with "Noticing that the sum of the digits of 8091 is 18, we can divide 8091 by 9, yielding 899. Testing all prime numbers up to <math>\sqrt{899} \approx 30</math>, we see that 899 i..."
 
Dividend (talk | contribs)
mNo edit summary
 
Line 1: Line 1:
==Solution==
Noticing that the sum of the digits of 8091 is 18, we can divide 8091 by 9, yielding 899. Testing all prime numbers up to <math>\sqrt{899} \approx 30</math>, we see that 899 is divisible by 29.  
Noticing that the sum of the digits of 8091 is 18, we can divide 8091 by 9, yielding 899. Testing all prime numbers up to <math>\sqrt{899} \approx 30</math>, we see that 899 is divisible by 29.  



Latest revision as of 17:06, 14 January 2020

Solution

Noticing that the sum of the digits of 8091 is 18, we can divide 8091 by 9, yielding 899. Testing all prime numbers up to $\sqrt{899} \approx 30$, we see that 899 is divisible by 29.

\[8091=9\cdot899=3^2\cdot29\cdot31\]

Therefore, the largest prime divisor of 8091 is $\boxed{31}$