Factorial – Texas Instruments TI-84 User Manual

Page 84

Chapter 2: Math, Angle, and Test Operations

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

(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+1

à2 is an integer ‚ 0.