**1. Can calculators evaluate factorials?**

Calculators will evaluate factorials from 0! which is equal to 1

through to 69! which is equal to 1.711224524 × 10^{98.}

**2. Do I have to use factorials and formulae to work out arrangements.?**

It is possible to write out all of the possibilities but much easier to use the methods demonstrated in Topics 33 and 34.

e.g. In how many ways can four different CDs be arranged on a shelf?

The possibilities are:

By counting , there are 24 possible arrangements.

Much easier to use factorials!

There are 4! = 4 × 3 × 2 × 1 = 24 ways in which the CDs can be arranged.