Writing numbers in words is very simple once you learn how to write specific numbers, which you can then use to write other numbers.
These are the numbers you will need to know.
1=ONE 
As you can see some of the number from 1 to 9 are used to write the numbers from 1119. However, only parts of the number has been used to make part of the number. Numbers above 20 make full use of 2 or more numbers, for example 21 is written twentyone, and this number uses the numbers twenty and one to make twentyone. 
2=TWO 

3=THREE 

4=FOUR 

5=FIVE 

6=SIX 

7=SEVEN 

8=EIGHT 

9=NINE 

10=TEN 
You will only need this number to make numbers above 100. 
11=ELEVEN 
None of the numbers up to nineteen are made up of any numbers but are made using parts of numbers. 
12=TWELVE 

13=THIRTEEN 

14=FOURTEEN 

15=FIFTEEN 

16=SIXTEEN 

17=SEVENTEEN 

18=EIGHTEEN 

19=NINETEEN 
This is the last number that is made up of parts of numbers. 
20=TWENTY 
