Texas Instruments TI-84 Plus Guide Book

Chapter 2: Math, Angle, and Test Operations 81
nCr (number of combinations) returns the number of combinations of items taken number
at a time.
items and number must be nonnegative integers. Both items and number can be
lists.
items nCr number
Factorial
FactorialFactorial
Factorial
! (factorial) returns the factorial of either an integer or a multiple of .5. For a list, it returns
factorials for each integer or multiple of .5.
value must be ‚L.5 and  69.
value!
Note:
The factorial is computed recursively using the relationship (n+1)! = n…n!, until n is
reduced to either 0 or L1/2. At that point, the definition 0!=1 or the definition (L1à2)!=‡p is
used to complete the calculation. Hence:
n!=n…(nN1)…(nN2)… ... …2…1, if n is an integer ‚ 0
n!= n…(nN1)…(nN2)… ... …1à2…‡p, if n+1à2 is an integer ‚ 0
n! is an error, if neither n nor n+1à2 is an integer ‚ 0.

Texas Instruments TI-84 Plus Specifications

General

Battery type	AAA
Power source	Battery
Number of batteries supported	4
Type	Graphing
Cover	No
Form factor	Pocket
Control type	Buttons
Product color	Black
USB port	Yes
USB 2.0 ports quantity	1
Digits	- digits
Display number of lines	8 lines
Display number of characters	16
RAM capacity	0.024 MB
ROM capacity	0.480 MB
Storage media type	-