The swift magic calculator to trick your friends
How to use:
First type in your friends phone number, then click the equals(=) sign. This will save the number in the phone. But if you close the app, you will have to reenter. Then ask your friends random personal questions in which they respond in a number. So for example, aks them their house number, or their shoe size or the number of friends they have. Do random operations in between the numbers. Then click the equals sign again. That will pull up the saved number. Watch them grin.