# Re: Number validation issue

Discussion in 'Python' started by Morten Engvoldsen, Feb 22, 2013.

1. ### Morten EngvoldsenGuest

Hi,
My below code is wrong :

elif mod == 11:
>> if not len(checknum)!= 11:
>> return False
>> weights = [5, 4, 3, 2, 7, 6, 5, 4, 3, 2, 1]
>> return (sum(w * int(x) for w, x in zip(weights, checknum)) % 11)

==0

it works for 9 digit number , not 11 digit number, so i have changed the
code and sending again with correct code with valid number:

def is_valid_number(checknum):
weights = [3, 2, 7, 6, 5, 4, 3, 2, 1]
return (sum(w * int(x) for w, x in zip(weights, checknum)) % 11) == 0

is_valid_number("123456785")

This code validate this 9 digit number "123456785" with below algorithm:

To verify the number use the following weights from right to left:
1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7...
Multiply each digit by its corresponding weight. Add the results together.
For the number to be correct the
total must be divisible by 11.
Field with control digit 1 2 3 4 5 6 7 8 5
Weight 3 2 7 6 5 4 3 2 1
Produce +3 +4 +21 +24 +25 +24 +21 +16 +5 =143
The sum must be divisible by 11 (143 divided by 11 leaves a remainder of
0).

So i am looking for solution how i can change this code to validate with
weight 1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7... from
right to left for any length of number. This code validate only 9 digit
number.

Sorry for inconvience

Morten Engvoldsen, Feb 22, 2013