Simple addition mistakes are my favourite! Replace ...55555 + ...5555 with ...99999 + 1 or ...5555 + ...44445 or something, I'm sure you can figure it out.
edit 2: Yes, you'll have to slightly change the algebra to prove that math breaks when you replace the numbers above. I have full confidence in you.
Proof some infinities are bigger than other infinities: http://youtu.be/lA6hE7NFIK0
