If you'll notice, for age most of the time you will just add the ending -sai.
*- denotes irregularity
#: romanji/ # years old
0: zero (pronounced "zeh roh")
1: ichi/ *issai
2: ni/ nisai
3: san/ sansai
4: yon/shi / yonsai
5: go/ gosai
6: roku/rokusai
7: nana/shichi /nanasai
8: hachi/ *hassai
9: kyuu/ kyuusai
10: jyuu/juu / juusai
10-19: juu+ number (ex: 15: jyuu-go) + -sai
20: ni jyuu/ *hatachi
21- 99: number+ jyuu+number (ex: 65- roku jyuu go) + -sai
100: hyaku
1,000: sen
10,000: man (pronounced "mah-n")
(Any variation on these numbers follows the same pattern.)
Try a few yourself! (Post responses directly in this thread.)
a. 24 b. 78 c. 13 d. 189 e. 1,546 f. 27, 915
Now try a-c as ages. ^_^
