Let $a= 2^{25}$, $b= 8^8$ and $c= 3^{11}$.
 
Now order the letters so that we get  ${?}< {?}< {?}$
 
 
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
 
 

This problem is taken from the UKMT Mathematical Challenges.