The numbers 1, 3, 3², 3³,...,3¹⁰ are written on a blackboard.
We are allowed to erase any two numbers and write their difference instead (this is always a nonnegative integer.)
After this procedure has been repeated ten times, only a single number will remain.
What values could this number have?

Edited on September 16, 2015, 12:40 pm

Posted by Steve Herman on 2015-09-16 12:14:32