The difference between 18 and 17 is: 
The difference between 42 and 30 is: 
The difference between 19 and 17 is: 
The difference between 18 and 17 is: 
The difference between 28 and 17 is: 
The difference between 18 and 17 is: 
The difference between 20 and 19 is: 
The difference between 18 and 17 is: 