This program is supposed to do some basic math like absolute value, comparison, addition, subtraction and, that is our homework, multiplication on arbitrary, depending on free memory..., integers.
The new implemented multiplication in the library largeint.h is used to accelerate computing the faculty of a number. 
The naive implementation just uses additions and is supposed to be improved.

The original sources can be found on http://www.or.uni-bonn.de/~vygen/lectures/alma1ws12.html