The difference between 21 and 18 is: 
The difference between 47 and 33 is: 
The difference between 29 and 18 is: 
The difference between 21 and 10 is: 
The difference between 21 and 18 is: 
The difference between 21 and 18 is: 
The difference between 24 and 11 is: 
The difference between 21 and 18 is: 