Calculator

This is a simple calculator.
- It supports a mini calculator on any screen.
- It supports arithmetic expressions such as +, -, x, ÷, /, (, ).
- It supports percent operation and memory buttons.
- It supports a scientific calculator.
- It supports digit grouping separator(comma, space, Apostrophe)
- It supports digit grouping method (987,654,321.012 or 9,8765,4321.012 or 98,76,54,321.012)
- It supports the calculation history.
- EvalEx Calculator : Calculate by entering variables and formulas
```
Revenue = 120,000
Cost = 70,000
Profit = Revenue - Cost
Tax = Profit * 0.1
NetProfit = Profit - Tax
```

[Percent operation]
100x3%=3 (3% of 100)

[Memory buttons]
M+ : memory + result
M- : memory - result
MR : memory return
MC : memory clear
MS : memory set

[Clear button]
C : clear
AC : all clear (clear result and memory)

[Scientific Calculator]