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[PPS Numbers]

What is a PPS Number?

The format of the number is a unique alphanumeric in the general form 8765432A. The number is assigned at the registration of birth of the child and is issued on a "Social Services Card" often when a child reaches the legal age of employment, currently 16, otherwise a "Letter of Entitlement" is issued. The same format was used by the [rish Minister for Education and Science|Department of Education and Science as the "Pupil Number" since 1994 and this caused some concern and confusion as it was in the same format and used the same check character formula, but more often different from the PPS No. In August 2000 the department instigated a program to remove the Pupil Number and replace it with the PPS No in future on records. The format is 7 numeric characters (including leading zeros), a check character and sometimes a second letter, which if it exists, will be a W. This extra letter was used for women - "W" from "wife" - who married and automatically adopted the same number as their husband, though this practice stopped in 1991 chiefly due to equal rights concerns. The present policy is that these W numbers are eliminated when the bearer comes in contact with social welfare or tax offices and are replaced by the original number. Alternatively a new number is issued when none is traceable. Sometimes, an extra character (either a T or an X) may be used to relate to specific employment or welfare situations such as a husband & wife being employed by the same company, or an employee being employed twice by the same company (where two separate PPS numbers would be needed for reporting purposes) or in a welfare situation, where a separated spouse receives some of the customer's payment on their own behalf.

Checksum Character

The format of the PPS number is seven digits plus a check character. A second character may be used. If so it is always a 'W'. The check character is calculated using a weighted addition of all the numbers and modulus calculation. It therefore checks for incorrectly entered digits and for digit transposition (digits in the wrong order will alter the sum due to weightings).

Calculating the Checksum Character

In reverse order, each digit is multiplied by a weight, 2, 3, and so on until the first digit is multiplied by 8. Add up each result. Divide by 23 and the remainder (modulus 23) will indicate the character position on the alphabet. Thus the PPS number 1234567 will be calculated as the sum of 7*2, 6*3, 5*4, 4*5, 3*6, 2*7 and 1*8. This 112 when divided by 23 leaves a remainder of 20. The twentieth letter of the English alphabet is 'T'. The correct PPS number is therefore 1234567T. Where the remainder is zero, the check letter is W. (From Wikipedia)

[Credit Cards]

(LUHN Formula (Mod 10) for Validation of Primary Account Number)

Checksum Digit

This outlines the procedure/algorithm for Verifying the accuracy and validity of credit card numbers. Most credit card numbers are encoded with a "Check Digit". A check digit is a digit added to a number (either at the end or the beginning) that validates the authenticity of the number. A simple algorithm is applied to the other digits of the number which yields the check digit. By running the algorithm, and comparing the check digit you get from the algorithm with the check digit encoded with the credit card number, you can verify that you have correctly read all of the digits and that they make a valid combination.

Calculation Steps

The following steps are required to validate the card number:
  1. Double the value of alternate digits of the primary account number beginning with the second digit from the right (the first right--hand digit is the check digit.)
  2. Add the individual digits comprising the products obtained in Step 1 to each of the unaffected digits in the original number.
  3. The total obtained in Step 2 must be a number ending in zero (30, 40, 50, etc.) for the account number to be validated.

Example

To validate the primary account number 49927398716:

Major credit cards

CARD TYPE Prefix Length Check digit algorithm
MASTERCARD51-5516 mod 10
VISA413, 16 mod 10
AMEX34
37		15 mod 10
Diners Club/Carte Blanche300-305
36
38 		14mod 10


Last updated: 20150326-11:55