Usually, for arithmetical operations, standard built-in types as integer, float etc are enough. However, in some cases, the operands are so big, that they don't fit in any built-in type. For example:
  -Computing fundamental mathematical constants such as π to millions or more digits.
  -Investigating the precise behavior of functions where certain questions are difficult to explore via analytical methods.
  -Rendering fractal images with extremely high magnification.
In the above cases, Arbitrary-precision arithmetic would be the solution. Let's try to simplify a scientist's life with a calculator which can operate numbers with any given length.

Implement a calculator with a graphical user interface, which provides a user with all standard operations:
  -Addition
  -Subtraction
  -Multiplication
  -Division
Your application should be able to manipulate integers of any length.

The source file is:
BigNumCalc.cpp