She knew:

• It had 4 or 5 digits.
• It used 4 or 5 different digits.
• The first digit is 4 or 5.
• The second digit is 4 or 5 and none of the other digits is smaller.
• The number is 4 or 5 times a prime number.
• If you reverse the order of the digits, the resulting number has 4 or 5 prime factors, all different.
• In 4 or 5 of these facts, the "4" is the correct number.

What is Susan's PIN code?

Quite right. In my rush to complete the manual solutions, I took the reversal of 1367, 7631 = 13*587, instead of the reverse of 5468. Hence, no doubt, the ambiguity in the title, i.e. 5468 or 54776.

Are we done now, Charlie?

Edited on November 18, 2010, 5:12 pm

Posted by broll on 2010-11-18 17:08:44