This App is a calculator for rational numbers. Every number used in the calculation as well as results of the calculation must be a rational number written as a fraction of two integers. The calculator can calculate arbitrary large rational numbers as long as there is enough memory for the calculation. It is great to know that 100! = 9332621544394415268169923885626670049071596826438162146859296389521759999322991560894146397615651828625369792 0827223758251185210916864000000000000000000000000.