MCalculator - Calc Prank

You would like to prank your friend, then this is the perfect app. First you need to chose a phone number or create a custom number and then you can just your friend questions such as: 
How many siblings do you have? 
How old are you? etc.
The answer of these questions can be added, subtracted, multiplied and divided. After pressing "=" (equal) the app show the previously chosen number.