Counting

1oneichi
2twoni
3threesan
4fourshi
5fivego
6sixroku
7sevenshichi
8eighthachi
9ninekyu
10tenju

For 11 to 19, the number is translated as 'ten plus one'
or 'ten plus two', etc.

11elevenichi
12twelveni
13thirteensan
14fourteenshi
15fifteengo
16sixteenroku
17seventeenshichi
18eighteenhachi
19nineteenkyu

At 20, the number is 'two ten's, or ni ju.
This pattern continues to 99.

20twentyni ju
21twenty oneni juichi
22twenty twoni juni
23twenty threeni jusan
.........
99ninety ninekyu jukyu
100one hundredhyaku