Math module in Python contains a number of mathematical operations, which can be performed with ease using the module. math.perm() method in Python is used to get the number of ways to choose k items from n items without repetition and with order. It Evaluates to n! / (n – k)! when k <= n and evaluates to 0 when k > n.
This method is new in Python version 3.8.
Syntax: math.perm(n, k = None)
Parameters:
n: A non-negative integer
k: A non-negative integer. If k is not specified, it defaults to NoneReturns: an integer value which represents the number of ways to choose k items from n items without repetition and with order. If k is none, method returns n!.
Code #1: Use of math.perm() method
# Python Program to explain math.perm() method # Importing math module import math n = 10k = 2 # Get the number of ways to choose # k items from n items without # repetition and with order nPk = math.perm(n, k) print(nPk) n = 5k = 3 # Get the number of ways to choose # k items from n items without # repetition and with order nPk = math.perm(n, k) print(nPk) |
90 60
Code #2: When k > n
# Python Program to explain math.perm() method # Importing math module import math # When k > n # math.perm(n, k) returns 0. n = 3k = 5 # Get the number of ways to choose # k items from n items without # repetition and with order nPk = math.perm(n, k) print(nPk) |
0
Code #3: If k is not specified
# Python Program to explain math.perm() method # Importing math module import math # When k is not specified # It defaults to n and # math.perm(n, k) returns n ! n = 5 nPk = math.perm(n) print(nPk) |
120
Reference: Python math library