Too Many!

Time for a first post in here yes? :p Anyway, this riddle was tossed my way the other day so... time to share it with all of you.

You buy a newly born mouse from a pet store...
It takes 2 months for a mouse to be able to give birth...
And it gives birth every month after that...
To 12 baby mice... o_O
Which in turn will give birth, etc.

So... How many mice will you have after 10 months?

My flippant answer to this was Too Many! Which is kind of correct, but not really... What's your answer? :p

End