#    
##    

The **`math.perm()` function** in Python is used to return the number of permutations of _k_ items from a group of _n_ items, i.e., it helps us figure out the number of ways in which we can choose k items from n items with order and without repetition. 

The **`math` module** in Python contains a number of mathematical operations that can be performed very easily. Amongst some of the most important functions in this module, the `perm()` function has its own importance. 

>This function was recently introduced Python 3.8. You can use the `math.perm()` function in Python versions 3.8 and above.


## Syntax
``` python
math.perm(n, k)
```

## Parameters

- `n`: Total number of items. Needs to be a non-negative integer.
- `p`: Number of objects to be selected. Needs to be a non-negative integer. 

> The parameter `k` is optional. If we do not provide it, this method will return `n!`. For example, `math.perm(4)` returns `4!`, i.e., `24`.

## Return value

The function returns an integer that corresponds to the result from the following formula:

$$math.perm(n, k) = nP_{k} =  
\frac{n!}{(n-k)!}$$


## Code

Let us look at the code snippet below.


# Import math Library
import math

# Initialize n
n = 7

# Initialize k
k = 5

# Print the number of ways to choose k items from n items
print (math.perm(n, k))




#  Explanation

* In *line 2,* we imported the `math` module in Python.

* In *line 5,* we initialize the number of items to choose from (n).

* In *line 8,* we initialize the number of items to choose (k).

* In *line 11,* we use the `math.perm()` function and compute the requisite.

##  
##   
### Output
The output is: 

$7P_{5} = \frac{7!}{(7-5)!} = 7!*6!*5!*4!*3! = 2520$


In this way, we can use the `math.perm()` function in Python to compute the permutation of any two given numbers. 





How to use the math.perm() function in Python

math.perm() in Python calculates permutations, introduced in Python 3.8, using the formula nP_k = n!/(n-k)!.