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Sunday, May 11, 2008

The Number Games


Number games are very important to most Singaporeans - many wish to be rich through 4-D, TOTO, Big Sweep and other games that Singapore Pools (and other illegal rivals) offer. It is inevitable that we are identified by numbers since computers are used in all public services and also private businesses. All of us have many identifiers and even our assets (or liability, I still cannot decide how to classify my car) like motor vehicles have identifier, also know as Vehicle Registration Number.

For motorists with deep pocket and a preferred number for their vehicles, LTA offers bidding for vehicle registration numbers. You can bid for a number for your new vehicle or existing ones. I know many motorists who decided to bid after receiving "lousy" system assigned numbers. So how much does the exercise cost? At least S$1,000 to bid for any number while the lucky numbers, the single-digit number and the low numbers will attract many bidders and thus, yield higher bids. There are also additional fees for retaining and exchanging Vehicle Registration Numbers between vehicles.

I was curious about how the suffix alphabet was computed and found the algorithm - each alphabet of the series yield an ASCII code (A = 65, B = 66, ...). Subtract it by 64 and multiple with a constant code for each position. Number value is also multiplied with a constant code. All the products are summed up and the remainder of the result when divided by 19 will yet the position of the 19-character string that determines the suffix. Check out the tool that illustrates how it is done.

If my name is Eric, I would love to have my Vehicle Registration plate showing "ER 1 C" but the alogorithm for the suffix alphabet turns up "T" so the legitimate plate is "ER 1 T". How about the intimidating "EV 1 L"? The legitimate plate is "EV 1 Y". Have you seen interesting Vehicle License plates?

7 comments:

Anonymous said...

yes, I saw vehicle with registration no. ER1T at Orchard area on Friday evening May 16...

skxly said...

Please ask if his name is Eric? 8-) I suppose that it is a luxury or sports car to have that plate.

nhyone said...

A car is an asset; you can sell it for cash. Your liability is your car loan.

skxly said...

Yes, you are right. I am still not satisfied with it as an asset since its depreciation is occurring at such a rapid rate. I would like to live and work in close proximity to eliminate the need to own a car.

kevin said...

Hey this is interesting! It's accurate for cars but when I tried with G series commercial vehicles, the suffix don't quite match up.

Btw out of curiosity, how'd you figure out the algo?

skxly said...

Kevin, I have tested with numbers from some Goods vehicles that I see this morning and found that the algorithm works too. You need to leave the first character blank if the series is G? and leading blanks if the number is less than four digits.

I reverse-engineered the algorithm from other tools found online. I believe the algorithm and weighting are provided to software firms and large firms to program data entry checking for capturing such personal data. A different weighting is used for NRIC (the prefix character + 7 digits) to compute the suffix character.

jonbong said...

Hi skxly! You're right on the part of the algorithm being provided to software firms and such. Being in the IT profession, I'd been dealing with implementations of such algorithms to come up with validation checks such as NRIC/FIN numbers, student admission numbers, frequent-flyer airline ticket numbers etc. I find it so interesting to see how such check digits are being implemented that I'm now compiling such implementations on my own as a personal project.

Thanks for providing a good tool too! I've tried your tool on a variety of vehicles (cars/motorcycles with old & new number plates, commercial/industrial, public/private buses and law/emergency/government-statutory board vehicles) and have found no errors so far. One other category that you might like to consider adding to the tool though is that of trailers (bearing the TRx prefix).