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### Social Insurance Number

```
Date: 7/3/96 at 11:40:52
From: Anonymous
Subject: Social Insurance Number

Make a valid Social Insurance Number that has 8 as its check digit.
```

```
Date: 7/3/96 at 23:13:36
From: Doctor Mike
Subject: Re: Social Insurance Number

Hello,

Revenue Canada's Internet Service publishes the SIN formula in

http://www.rc.gc.ca/E/pub/tg/t4028ed/t4028ed.html

as follows:
======
Information for Magnetic Media Filers
1995 - Computer Specifications for Data Filed on Magnetic Media

-  Invalid or missing social insurance numbers cause processing
delays. Included below is the formula we use to validate
this number.

Example
Employee's social insurance number (SIN): 550 911 895

Formula:                                  Assigned Digits

Digits                  Check
digit
Recipient's SIN
(Exclude the check digit,
position 9, from calculation) 5  5  0  9  1  1  8  9          5
==
5     9     1     9
Multiply every second digit
by 2                         x2    x2    x2    x2
--    --    --    --
10    18     2    18

Cross add the resulting digits (1 + 0 + 1 + 8 + 2 + 1 + 8) = 21

Cross add the intervening digits (5 + 0 + 1 + 8)           = 14
--
Total                                                        35

Subtract from the next highest number ending in zero         40
--
Check digit (i.e., 40 - 35 = 5)                               5
======
Following this example, 550 911 598 would satisfy the question.
There are many others.  Perhaps yours? I hope this helps.

-Doctor Mike,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
High School Permutations and Combinations

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