Reverse Number Without Strings In Python

reverse_num.py

# To the not-so-mathematically-inclined, this function may look like pure witch-
# craft.  That's why I shall describe how it works.
#
# Let's say we start with an initial number of `13`, we expect an output of `31`,
# right? Let's see:
#
# reverse_number(13)
#
# num = 13
# reversed_num = 0
#
# first loop of while loop:
#     reversed_num *= 10 (reversed_num = 0)
#     reversed_num += num % 10 (reversed_num = 3;   13 % 10 = 3.  % = modulus, remainder of divion)
#     num /= 10 (num = 1;   We remove the three because we extracted it above).
#
# second loop of while loop:
#     reversed_num *= 10 (reversed_num = 30;   3 * 10 = 30)
#     reversed_num += num % 10 (reversed_num = 31;   1 % 10 = 1)
#     num /= 10 (num = 0;    1 / 10 = 0)
#
# Third loop doesn't happen because num is now zero.  `reversed_num` now contains
# our fully reversed_number.
def reverse_number(num):
    reversed_num = 0
    while num != 0:
        reversed_num *= 10
        reversed_num += num % 10
        num = int(num / 10)
    return reversed_num