maths.digital_root
==================

.. py:module:: maths.digital_root


Functions
---------

.. autoapisummary::

   maths.digital_root.digital_root


Module Contents
---------------

.. py:function:: digital_root(number: int) -> int

   Return the digital root of a non-negative integer number.

   The digital root is the single-digit value obtained by repeatedly summing
   the decimal digits of number until only one digit remains. The input is taken by
   its absolute value, so negative numbers behave like their positive
   counterpart.

   >>> digital_root(0)
   0
   >>> digital_root(9)
   9
   >>> digital_root(38)
   2
   >>> digital_root(12345)
   6
   >>> digital_root(-45)
   9
   >>> digital_root(999999999999)
   9