Study Aids -
Stirling's approximation for factorials
Factorials can be approximated for large values of n using the
Sterling approximation which is given by:
This equation yields n! with a
relative error smaller
than 1/4 % for all integer values of n and with
a relative error smaller than 3.5 x 10-7 for n > 20.
The exact and approximate values for n = 1, 2, ... 10
and the relative error are provided in the table below.
© Bart J. Van Zeghbroeck, 1997