I Am Not a Number ...

In April, Stagecoach in South Wales announced that weekly tickets would no longer be issued from the machine, as has been standard practice pretty much since buses were invented. Instead, their customers were notified about 'smartcards', which would replace the ancient Chinese technology they've got used to.

I don't often buy a ticket for more than a day at a time, but I'm working on a project which has taken me the length and breadth of the Cynon Valley since Sunday. It made sense to buy a Megarider. At only £11.70 for a week, it was going to be far most cost-effective than buying several daily tickets. Thus I added their smartcard to my growing collection.

I've had Cardiff Bus's iff card since they were launched. I've only used it a few times, though. As you can only top it up on the day of travel – in a small number of city centre locations – or on the bus itself, it seems to be a bit of a half-arsed effort. I was expecting it to be something like the Oyster card, which Transport for London introduced several years ago, and which represents a real step into the twenty-first century. (As usual, here in Wales, we looked at what was going on in England, thought 'That's a good idea,' and then totally failed to implement said idea.) Instead, you have to queue up in the Spar opposite Queen Street station to put a fiver onto the card, then buy your one-day ticket on boarding the bus, and retain the paper copy when the driver gives it to you. Two out of ten for effort; must try harder.

Stagecoach's smartcard doesn't even have a groovy name. It's just called Stagecoach smart – which does exactly what it says on the tin, but isn't really a marketing/branding triumph. I don't know yet whether you can top it up online. Presumably you can, because the signs on the buses say that tickets for longer than a week can be obtained via the website. The posters advertising the card also tell passengers customers to register their new cards online, in case they get lost or stolen. That's a fat lot of good to the majority of people in Wales who have never used the Internet. But I digress …

No, what caught my eye was the incredibly long serial number printed on the reverse side. (I won't publish my number here, for obvious reasons.) Instead, I'll just tell you that it consists of a block of six digits, followed by three blocks of four digits each. That's eighteen digits.

Let's do some maths. Don't run away screaming – this isn't the sort of insane thing that John Nash does in A Beautiful Mind; it's more what my old maths teacher would call 'sums'. I can't even take the credit for this one. I was inspired by Prof. Douglas R. Hofstadter, who pointed out the absurdity of his credit card number in his Scientific American column, way back in about 1980.

If you have four digits, you can issue ten thousand uniquely numbered cards, ranging from 0 000 to 9 999. Six digits take you to one million (000 000 through to 999 999). Eighteen digits allow you to count up to 999 999 999 999 999 999 – in other words, one million million million minus one. Or, as we scientists would say, 10¹⁸ - 1.

At the time of writing, the estimated population of the planet Earth is 7.5 billion – 7.5 × 10⁹. A back-of-the-beermat calculation informs me that, using these eighteen-digit numbers, Stagecoach could issue somewhere in the region of 133 million smartcards to every man, woman and child currently alive.

As the late great Sir Terry Wogan used to say, Is it me?