Ah, a fun game, with math!

Scrolled through all of the comments, didn't find mention of the spelling mistake right at the top. Sorry, but spelling/grammatical errors often communicate sloppiness. Even when you worked very hard.

"Chosse your oponent"

perhaps:

Choose your opponent:"

and

"you win refresh to go again"

could be

"You won! Refresh to play again" -- you could even add a link to load the page again.

"sorry that was the wrong answer, the corect answer was:"

could have "correct", and a capital letter for "Sorry"