Polish Identity Card - Validation

Validation

The card number consists of 3 letters followed by 6 digits (for example, ABA300000), of which the first digit (at position 4) is the check digit.

Each letter has a numerical value, as shown below:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

The next step is to multiply each so obtained value by its respective "weight". The assigned weights for each position are

1 2 3 4 5 6 7 8 9 7 3 1 0 7 3 1 7 3

The remainder of the division by 10 of the sum of the weighted values should be equal to the check digit (indicated between asterisks in the example below).

Verification example (ID card number for this example: ABA300000):

Card number: A B A *3* 0 0 0 0 0 Value: 10 11 10 *3* 0 0 0 0 0 Weight: 7 3 1 0 7 3 1 7 3 Result: 70 33 10 0 0 0 0 0 0 Sum: 70 + 33 + 10 + 0 + 0 + 0 + 0 + 0 + 0 = 113

The remainder of the division of 113 by 10 equals 3 (113 mod 10 = 3), and is also equal to the first digit of the ID card number, so this ID card number is correct.