How to Calculate a Factorial in Excel with FACT

FACT counts the ways to arrange things — speaker orders, ranked shortlists and displays with repeated items.

You will learn to

• Count the orders of a full lineup
• Count ordered picks from a larger group
• Count arrangements when some items are identical

How it works

FACT(number) returns the factorial n! = n × (n-1) × … × 1. =FACT(5) is 120, the number of different orders for five speakers. FACT(0) is 1 by definition, and decimals are truncated, so FACT(5.9) is also 120.

Factorials combine into other counts. Ordered picks of k from n are FACT(n)/FACT(n-k) (what PERMUT returns), and arrangements with identical items divide by the factorial of each repeated group: FACT(6)/(FACT(3)*FACT(2)*FACT(1)) = 60. Factorials grow extremely fast — FACT(171) is too large for Excel and returns #NUM!.

=FACT(B2)