[Tutor] Function not returning 05 as string

[Ken G.]

I am sure there is an simple explanation but when I input
5 (as integer), resulting in 05 (as string), I get zero as the end
result. When running the code:

START OF PROGRAM:
Enter the 1st number:  5

05

0
END OF PROGRAM:

START OF CODE:
import sys

def numberentry():
     print
     number01 = raw_input("Enter the 1st number:  ")
     if number01 == "0":
         sys.exit()
     if  len(number01) == 1:
         number01 = "0" + number01
     print
     print number01
     return(number01)

number01 = 0
numberentry()
print
print number01
END OF CODE: