What you need to know for this case is that the calculator is using the scientific notation in two different ways: 
 Way 1: 
 

 Way 2: 
 

 Where, in both cases: 
 a, b: they are real numbers. 
 Therefore, for the following number:
 

 We have an equivalent way is: 
 

 Answer:
 

 The e refers to the exponent to which the base 10 is elevated.