Week Three Of a number too large to fit in this text box

Wow, I feel like I haven't slept in weeks--wait a second! I haven't! Funny how that happens. Okay so here we are in week three. Not much has happened in the sense that I am still trying to learn the language through Rosetta Stone and find a headset that doesn't reject my voice (You don't know how many awkward silences have followed me blurting out Japanese phrases in the middle of the day.). At least the headset problem isn't something that is solely mine, in fact the other three people I know taking this course all empathize. One of these days I will be struck by a bolt of tech-savvy lightening and everything will make sense.

Family:
Daughter = musumesan
Son = musukosan
Mother = okaasan
Father = otousan

People:
Girls = onnanoktachi
Boys = otokonoko
Men = otoko no hitotachi
Women = onna no hito
They = karera
Girls = kanojotachi
Friend = tomodachi

Numbers:
Zero = zero
One = ichi
Two = ni
Three = san
Four = yon
Five = go
Six = roku
Seven = shichi
Eight = hachi
Nine = kyuu
Ten = juu
Eleven = juuichi
Twelve = juuni

"How old are you?"
I will give you the template to this question but the only downer is that so far the ages to reply with are a little limited because I am only in unit two of the program but here we go!

Template:
Where the blank is is where kare or kanojo would be placed.
_______ wa nansai desuka.

Reply:
In this blank the number of choice would be placed.

________ desu.



Possible answers (Limited, yes I know.) :

Okay so as you can see the numbers here are different here than up there in writings previous but there's nothing I can really do about it. The numbers change yet again for other things but we'll just give you this example to start with.
One = issai
Two = nisai
Three = sansai
Four = yonsai
So here's the trick; they added sai to the end of the original number. Guess what five would be? Yeah, there you gosai (Bad joke...)!
Of course, it can never be quite that simple so there are some that are changed a little more than logic can help us newbies with.
Seven = nanasai
Eight = hassai

Examples:
Kanojo wa nansai desuka.
Yonsai desu.

Kare wa nansai desuka.
Hassai desu.


Okay I hope you can digest this week's lesson and I'll talk to you again in another seven days!
Bye for now!