Numbers 0 to 30

0    Zero
1    One
2    Two
3    Three
4    Four
5    Five
6    Six  
7    Seven
8    Eight
9    Nine
10    Ten
11    Eleven
12    Twelve
13    Thirteen
14    Fourteen
15    Fifteen
16    Sixteen
17    Seventeen
18    Eighteen
19    Nineteen
20    Twenty
21    Twenty-one
22    Twenty-two
23    Twenty-three
24    Twenty-four
25    Twenty-five
26    Twenty-six
27    Twenty-seven
28    Twenty-eight
29    Twenty-nine
30    Thirty

EXERCICES:

• http://www.languageguide.org/english/numbers/
• http://www.mathcats.com/explore/reallybignumbers.html