TTMath is a small library which allows one to perform arithmetic operations with big unsigned integer, big signed integer and big floating point numbers. It provides standard mathematical operations like adding, subtracting, multiplying, dividing. With the library also goes a mathematical parser to help you solving mathematical expressions.
TTMath is developed under the BSD licence which means that it is free for both personal and commercial use.
The main goal of the library is to allow one to use big values in the same way as the standard types like int or float. It does not need to be compiled first because the whole library is written as the C++ templates. This means only C++ developers can use this library and one thing they have to do is to use 'include' directive of the preprocessor. How big the values can be is set at compile time.