The ! Command

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Command Summary

Calculates the factorial of a number or list.

Command Syntax

value!

Menu Location

Press:

1. MATH to access the math menu.
2. LEFT to access the PRB submenu.
3. 4 to select !, or use arrows.

Calculator Compatibility

TI-83/84/+/SE

Token Size

1 byte

! is the factorial function, where n! = n*(n-1)! and 0! = 1, n an nonnegative integer. The function also works for arguments that are half an odd integer and greater than -1/2: $(-\frac1{2})!$ is defined as $\sqrt{\pi}$ and the rest are defined recursively. 69 is the largest number for which the calculator can perform the operation.

3!
     6
(‾.5)!
     1.772453851
Ans²
     3.141592654

The combinatorial interpretation of factorials is the number of ways to arrange n objects in order.

Error Conditions

• ERR:DOMAIN for any numbers except the ones mentioned above.

Related Commands

• nPr
• nCr

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