That's right, Spectrum BASIC did not have recursion. I don't recall the details of our implementation. Even if I find the backup (on audio tape or floppy disk), it won't be readable any more. AFAIR, we used a string to store the number. Contrary to my intention, I've written a Maple worksheet, using a set of digits (the natural choice for such a brute force approach, IMHO). Quick, but ugly. I'll post it in my blog.

Some 20 years ago, a restricted version of this challenge was posed in a science show on German public TV ("Kopf um Kopf"): arrange the digits 1,..,9 so that the number resulting from the first two digits (from the left) is divisible by 2, etc.. A friend of mine and me used a Sinclair Spectrum (8 bit home computer) and nested loops in BASIC to find the result... Just for fun, we didn't actually take part in the competition. I still know the result, so I won't write a Maple proc, but maybe anyone else might be interested.