Which operation involves a bang or a shriek?

Using an Exclamation mark as theses are alternative terms for the symbol

In maths it indicates a factorial which has the exclamation mark as its symbol.
A factorial of a positive whole number is simply the result of multiplying all the whole numbers from one up to it, so factorial 5, written 5! and sometimes called five bang or five shriek equals 1x2x3x4x5 = 120.

The gamma function extends the concept to non-whole numbers.

For some people, though, all maths involves a shriek.