The difference between 81 and 42 is: 
The difference between 83 and 57 is: 
The difference between 89 and 42 is: 
The difference between 81 and 40 is: 
The difference between 51 and 42 is: 
The difference between 81 and 72 is: 
The difference between 89 and 40 is: 
The difference between 81 and 42 is: 