TI-83 Plus Math, Angle, and Test Operations 94
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)! = nän!,
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!=nä(nN1)ä(nN2)ä ... ä2ä1, if n is an integer ‚0
n!= nä(nN1)ä(nN2)ä ... ä1à2ä‡p, if n+1à2 is an integer ‚0
n! is an error, if neither n nor n+1à2 is an integer ‚0.
(The variable n equals value in the syntax description above.)