# The Perm Function Of Math Module In Python

perm()

perm(n, k=None)

## Parameters:

n – Number of items

k – Number of items to be chosen.

## Return value:

Returns the number of ways to select ‘k’ items from number of items ‘n’, with order and without repetition.

## Overview:

• Like the comb() function perm() is a combinatoric function.
• The perm() function of Python math module returns the number of ways to select ‘k’ items from number of items ‘n’, with order and without repetition.
• The computation is given by: n! / (n - k)!, where k <= n; returns zero when 'k' is greater than 'n'.
• When ‘k’ is None or when ‘k’ is equal to ‘n’, the function returns n! .

## Example:

 # Example python program to compute permutations -  Number of ways to choose k items from n # items import math   totalItems      = 52; # n itemsToChoose   = 5;  # k   # Number of ways to choose k items from n items (without repetition and with order) permutations    = math.perm(totalItems, itemsToChoose);   print("Number of ways to choose %d items(k) from %d items(n)(without repetition & with order):"%(totalItems, itemsToChoose)); print(permutations);

## Output:

 Number of ways to choose 52 items(k) from 5 items(n)(without repetition & with order): 311875200