# TI-BASIC:Factorial

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Jump to navigationJump to search**Command Summary**

Calculates the factorial of a number or list.

**Command Syntax**

*value*!

**Menu Location**

Press:

- MATH to access the Math menu.
- LEFT to access the PRB submenu.
- 4 to select !, or use arrows.

TI-83/84/+/SE

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: <math>(-\frac1{2})!</math> is defined as <math>\sqrt{\pi}</math> and the rest are defined recursively.

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.