bpo-37128: Add math.perm(). (GH-13731)
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 8c68370..c5a77f1 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -207,6 +207,19 @@
of *x* and are floats.
+.. function:: perm(n, k)
+
+ Return the number of ways to choose *k* items from *n* items
+ without repetition and with order.
+
+ It is mathematically equal to the expression ``n! / (n - k)!``.
+
+ Raises :exc:`TypeError` if the arguments not integers.
+ Raises :exc:`ValueError` if the arguments are negative or if *k* > *n*.
+
+ .. versionadded:: 3.8
+
+
.. function:: prod(iterable, *, start=1)
Calculate the product of all the elements in the input *iterable*.