License plate check digit

last SG · 2003-10-05T16:37:32+00:00

Can't be because Volvo had already absorbed Leyland at that time. If SBS was comprehensive with the LO 3x, then why would they order over 400 VO 3x? The VO i...

pkchukiss SG

How do I check the check digit on a bus's license plate?

What I know is that numbers terminating in 01 have an A, and so on. What is the algorithm they use to assign check digits?

AntiDennisLance SG

No, numbers ending with 01 dont mean they end with A. I dont know what is the official algorithm, but I have my own way of calculating, which is just as 100% accurate.

To long winded to describe here.

pkchukiss SG

Maybe I am just generalising, because I happened to see SBS 9401 A on service 31…

AntiDennisLance SG

Yeah but for example, SBS101 is T, SBS301 is H, TIB1101 is T, TIB301 is P, TIB1001 is Z etc

Superbus SG

Hello,

SBS9401 's check digit is T. (SBS 9401 T)

Anyone can guess what's so special about this bus? (oh come'on bus fans, let's give our friends who sometimes heck-care about buses Mr. Green to guess here)

Cheers and warm regards

SBS9816E SG

Hmm, this is how the algorithm goes for SBST...

A, Y, U, S, P, L, J, G, D, B, Z, X, T, R, M, K, H, E, C

From this list, the following letters are out: F, I, N, O, Q, V, W

I don't know why some letters from the algorithm are left out, but I know why I and O are left out. This is because I resembles like '1', and O resembles '0'. As a result, both letters are omitted.

Also, if you observe the algorithm through one or two sets, you might find out that some letters are left out from different sets of regos (e.g. 9810X, 9811T, 9812R, 9813M, 9814K, and 9828X, 9829T, 9830M, 9831K) The second set has left out the letter 'R'.

off_service SG

How about sharing it with us? I'm sure many of us here are interested.. We would gladly appreciate it if you do. Smile

AntiDennisLance SG

Okay, let me get home and dig up the text file i wrote sometime ago. Too lazy to re-type everything. Will post it here sometime tonight.

SBS9818A SG

9401T

AntiDennisLance SG

Alright, my own algorithm for deriving the check digit is here. Before you read it, this is an important DISCLAIMER:

A. I did NOT glean the info from espionage or any illegal way. I derived the algorithm through continued observations of many license plates (including private car license plates) of vehicles registered in Singapore over long periods, plus a good pattern sequencing intuition.

B. Anyone with a good observation skills can possibly similarly derive this method of determining vehicle check digits.

C. Since the method I describe here is rather long and tedious, this is probably NOT the official method or formula for deriving check digits. Although the method described here is 100% accurate, the official method is probably more direct and terse, possibly expressed in a mathematical formula.

Okay, on to my algorithm:

========================
The rule applies to ALL types of vehicle license plates in Singapore EXCEPT the following series:

1. TP-XXXX
2. ROV-XXXX
3. MID-XXXXX
4. S-XXXX-CD
5. XXXX-S

Rules for deriving check digits:

1. The alphabets used for the check digits of vehicles in singapore are:
ABCDEGHJKLMPRSTUXYZ

2. The starting check digit of each series is arbitrary. e.g. TIB series starts with E, SBS series starts with Z.

3. The ordering of the digits goes backwards and skips two digits between each consecutive number. Hence in the TIB series, one complete ordering cycle will be as follows:

ECAYUSPLJGDBZXTRMKH - ECAY.....

4. The derivation of each number's check digit from the next follows these rules, each with a higher priority over the other:

a. Between every 999th to the next '000th, the same digit is used.
e.g. since TIB999 is B, TIB1000 is also B

b. Between every 99th to the next '00th, skip to the next 8th digit in the cycled ordering
e.g. since TIB199 is T, TIB200 is Y

c. Between every 9th to the next '0th, skip 2 digits in the cycled ordering
e.g. since TIB29 is B, TIB30 is X

d. Between every other type of consecutive number, skip to the next digit in the cycled ordering
e.g. since TIB278 is Z, TIB 279 is X
========================

Hence by going through the derivation rules, certain short cuts can be derived:

a. From every X number to the (100 + X), skip 2 digits in the cycled ordering
e.g. TIB1 is E, hence TIB101 is A

b. From every X number to the (1000 + X), skip 12 digits in the cycled ordering
e.g. TIB1 is E, hence TIB1001 is Z

There are also other notable interesting observations:

1. The SBS series is always 1000 ahead of the TIB series.
e.g. SBS100 is X, TIB1100 is also X
e.g. SBS41 is H, TIB1041 is also H
Hence TIB(1000+X) always have the same check digit as SBS(X)

2. Since the ordering is fixed, any series with the same check digit for the starting number WILL HAVE THE SAME CHECK DIGITS all the way for all the numbers 0-9999.
e.g. the TIB, GP, YD, SBM, SCF, SCY, SH series are all TOTALLY IDENTICAL.

SBS9818A SG

Cheem!

off_service SG

Originally posted by AntiDennisLance:
[1. The SBS series is always 1000 ahead of the TIB series.
e.g. SBS100 is X, TIB1100 is also X
e.g. SBS41 is H, TIB1041 is also H
Hence TIB(1000+X) always have the same check digit as SBS(X)

[/b]

Not exactly. Some Tibs 600 series are similar to those of SBST scanias, e.g.

TIB 631 L, SBS 31 L
TIB 674 M, SBS 74 M

AntiDennisLance SG

You are only half correct. You are correct on the point that TIB601Z to TIB999 is the same as SBS1Z to SBS399B, but it does NOT invalidate the rule that TIB(1000+X) is always the same as SBS(X). You are merely stating the dervied property that for any TIB number whose last 3 numerical digits are 600 and above, TIB(X) will have the same check digit as SBS(X-600).

To demonstrate this fact, lets take an example stemming from the number 631 from SBS. If you go through the check digit derivation, you will find that the check digit for TIB1631 (1000 + SBS631) is E. The check digit for SBS1031 (TIB1631 - 600) is also E, but at the same time, back to itself, the check digit for SBS631 is also E !!

Do you see what I mean?

I know that TIB1631 does not exist yet, but you can go through the calculations yourself to see that the check digit is indeed E.

In summary ->

SBS631E, TIB1631E -> validates the property that TIB(1000+X) is the same as SBS(X)

TIB1631E, SBS1031E - > validates the property that for any TIB number whose last 3 digits are 600 and above, TIB(X) is the same as SBS(X-600).

Hence both properties are co-existent.

The second mentioned property does not apply for any TIB number whose last 3 digits are 599 and below. You can do the calculations yourself to see what I mean. For example, since the last three digits of TIB1201 is below 600, TIB1201 (M) is not the same as SBS601 (S).

AntiDennisLance SG

double post, sorry

off_service SG

Roger that.

pkchukiss SG

It is Singapore's first Volvo Olympian superbus, opened by Teo Chean Hean in 1994 (forgot what date).

Now I was absolutely positive on the check digit being A. Nevermind, I will try to keep a look out for that bus and confirm.

It seems that there is another bus 9402 on service 31 (okay, I skipped the check digit, I think I embarrassed myself enough).

[edited]Shameful mistake spelling "superbus" as "superbos"[/edited]

Superbus SG

Well, you are correct that it is launched by R-Adm Teo Chee Hean. However, it isn't the first Volvo Olympian Superbus in Singapore. The first is SBS9200G, new in 1994. SBS9401T is the one used to launch the "Superbus" series.

SBS9402R also operates on Service 31.

Cheers and warm regards

AntiDennisLance SG

The check digit is T. I have not seen the bus, but by calculations it is T (SBS9600K -> SBS9500R -> SBS9400X -> SBS9401T, or, an other way of deriving, SBS9000S -> SBS9100L -> SBS9200G -> SBS9300B -> SBS9400X -> SBS9401T). In the same way TIB440 is X, TIB441 is T.

It could be possible you saw it as A because SBS could have printed the license plate wrong for a period. In the past there had really been wrongly printed license plates. TIB320J wrongly printed as TIB320T, or TIB531S wrongly printed as TIB531P (currently already rectified) etc

SBS9818A SG

Another observation:

SBS (9300+X) = SBS (X)
For example, check alphabet for SBS 9816 is E, and check alphabet for SBS 516 is also E.
Also, check alphabet for SBS 9580 is J, and check alphabet for SBS 280 is also J

AntiDennisLance SG

Originally posted by SBS9818A:
Another observation:

SBS (9300+X) = SBS (X)
For example, check alphabet for SBS 9816 is [b]E, and check alphabet for SBS 516 is also E.
Also, check alphabet for SBS 9580 is J, and check alphabet for SBS 280 is also J[/b]

Yes due to the ordering algo, there are a lot of such similar sequences appearing within a series. Another interesting one is SBS3535E, SBS7035E etc