Zero-padder implementation in Python using math functions

caio-padder.py

import math

def main():
    while True:
        inputStr = input('Type a number: ')

        if inputStr == '':
            break

        inputNumber = int(inputStr)

        a = inputNumber
        if inputNumber % 10 == 0:
            a = inputNumber + 1
        number = (4 - math.ceil(math.log10(a + 0.2))) * '0' + str(inputNumber)
        print(str(inputNumber % 10) + ' ' + str(math.log10(a)) + ' ' + str(math.ceil(math.log10(a))) )

        print('Number zero-padded with 4 digits: ' + number)


if __name__ == '__main__':
    main()