need help with making a validating function

[ichabod801]

isdigit returns True if the string is all digits, but only if you call it (num.isdigit()). It's not clear exactly what you are trying to do, but if you need to see that the number is 9 digits long, you want len(num) == 9. Your atempt variable is just going to cause errors, because you never define atempt anywhere and then try to test it. I would just do a while True: loop, and break when the number is valid. I would also indent that else clause to tie it to the if, not the while.