Extend your Calculator Version 3 project by adding the extra credit features listed at the end of Prof. Hagerty's Assignment #1. Implement a backspace button, a +/- button, and put an = at the end of the text label that shows what is sent to the brain.

In addition to Hagerty's Assignment #1, add any of the following keys for extra credit:
abs value, %, x², 10ⁿ, e^x, 1/x, factorial, ln (natural log), log (common log), & Mod

Sample Test Case:

• coming soon
  

You must hand in the following papers stapled in this specified order:

1. CalculatorBrain.m
2. CalculatorBrain.h
3. CalculatorViewController.m
4. CalculatorViewController.h

Turn in the project folder by copying it to your network HandIn folder.

Also, call the instructor to your computer and execute the program for him for a run-time grade.