What it means
n! is the product of the whole numbers from 1 to n, so 5! = 120. By convention 0! = 1. Factorials count arrangements: n different books can be ordered on a shelf in n! ways.
Read aloud in real formulas
C(n, k) = n! / (k!(n − k)!)
Aethel says
n choose k equals n factorial over the quantity k factorial times the quantity n minus k, factorial
the number of ways to choose k from n
eˣ = ∑ₙ₌₀^∞ xⁿ / n!
Aethel says
e to the power of x, equals the sum from n equals 0 to infinity of x to the power of n, over n factorial
the series for e to the x
Typing it
- LaTeX
- n!
- Unicode
- U+0021
Formulas that use it
Questions
How do you say ! out loud?
It is usually read “factorial”, and also “n factorial”.
What does ! mean in maths?
n! is the product of the whole numbers from 1 to n, so 5! = 120. By convention 0! = 1. Factorials count arrangements: n different books can be ordered on a shelf in n! ways.
How do you type !?
In LaTeX, write n!. Its Unicode code point is U+0021.