Albert remarked that even when it is turned upside down, the number plate of his car still made sense.

He observed that this would however increase the registration number on it by 8505.

Given, all of the four digits in the number is different, find out what was his car license number?

(In reply to Logical approach by Rick)

Sorry to be a pedant Rick, but 2 and 5 are also digits when upside down depending on the font used - think of a calculator.

Also, given the digit restrictions isn't the range of N 0125 to 1298.

To answer Levik's question about whether there is a 'formal logical way' of solving the problem rather than 'trial and error' I think that the answer depends on how one generally approaches 'trial and error'. To me Rick's theory is very formal and logical, but is also trial and error - eg is the first digit 0 (trial), no because.... (error).

Like most problems where a definitive formula does not naturally fall out, this one is solved through trial and error and like most trial and error solutions it is possible to apply some degree of logic to it (either formally or intuitively) rather than just picking numbers at random.

Posted by fwaff on 2003-02-06 21:34:03