"The two sides of this equation appear to be different, don't they?" asked Grandpa
I looked at the numbers he had written on a piece of paper and nodded in agreement.
2011 = 1012
"Can you prove to me that the equation is right?" He asked. "No silly thing like moving the digits!"
This time I knew what he was talking about. Do you?
Although @Stiv has given a great answer, Grandpa had a different logic and that also holds true for
211 = 112