COMBINThe COMBIN function returns the number of ways to choose some number of objects from a pool of a given size of objects.
n – The size of the pool of objects to choose from.
k – The number of objects to choose.
COMBIN is the standard combinatorics function typically notated nCk and read “n choose k”. This is equivalent to FACT(n)/(FACT(k)*FACT(n-k)).
MULTINOMIAL: Returns the factorial of the sum of values divided by the product of the values’ factorials.
FACTDOUBLE: Returns the “double factorial” of a number.
FACT: The FACT function returns the factorial of a number.