Code

__author__ = 'Zoap'

import math

def output_style(text):

    print("\n" + text)

def info():

    text = "This program allows you to search for the number of possible combinations of a pin number of length x, " \
        "given that you know one of the digits"

    output_style(text)

def search():

    loop = True

    while loop is True:

        text = "Input number to search for: "
        output_style(text)
        search_x = str(input())

        if search_x.isdigit():
            loop = False

        else:
            text ="Number to search for must be a number!"
            output_style(text)

    return search_x

def pin_length(search_x):

    loop = True

    while loop is True:

        text = "Input length of pin code: "
        output_style(text)
        pin = input()

        if pin.isdigit() is False:
            text = "Length must be a number!"
            output_style(text)

        elif int(pin) > 7:
            text = "Length can not be more than 7 digits!"
            output_style(text)

        elif search_x.isdigit() <= 0:
            text = "Length can not be equal to, or less than zero!"
            output_style(text)

        else:
            loop = False

    return pin

def check_stop(search_x, pin):

    loop = True

    while loop is True:

        stop = int((math.pow(10, int(pin))))

        if stop < int(search_x):
            text = "Length of pin makes the number to search for bigger than the possible number of variations!"
            output_style(text)
            search()

        else:
            loop = False

    return stop

def calc_forloop(search_x, stop):

    number_list = []

    # For every integer in range add int to list and convert to string
    for i in range(0, (stop + 1)):
        number_list.append(str(i))

    #For every str in list containing x, count x
    x_numbers = [a for a in number_list if search_x in a]

    # Percent of total numbers/digits in range containing digit x
    percent = len(x_numbers) / (stop / 100)

    print_total = "That is a total of " + str("%.2f" % percent) + "%" " of all numbers between 0 and " + str(stop)

    if int(search_x) >= 10:
        text ="There are a total of " + str(len(x_numbers)) +\
                " numbers between 0 and " + str(stop) + " containing the number " + search_x
        output_style(text)

    elif int(len(x_numbers)) is 1:
        text = "There are a total of " + str(len(x_numbers)) +\
                 " number between 0 and " + str(stop) + " containing the digit " + search_x
        output_style(text)

    else:
        text = "There are a total of " + str(len(x_numbers)) +\
                 " numbers between 0 and " + str(stop) + " containing the digit " + search_x
        output_style(text)
    text = print_total
    output_style(text)

def run_again():

    loop = None

    while loop is None:

        text = "Run again? y/n: "
        output_style(text)

        choice = input()
        if choice in ["y", "Y"]:
            loop = True
            running = True

        elif choice in ["n", "N"]:
            loop = False
            running = False


        else:
            text = "Invalid input"
            output_style(text)

    return running

def main():

    running = True

    while running is True:
        info()
        search_x = search()
        pin = pin_length(search_x)
        stop = check_stop(search_x, pin)
        calc_forloop(search_x, stop)
        running = run_again()
main()