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?

Your number does not work.  54476

5 digits
4 different digits
5 for 1st digit
4 for 2nd digit none smaller
4 times the prime 13619
4 factors of its reversal: 67445 = 5*7*41*47
The last bullet cannot be fulfilled.  If we put 4 there are 5 4s, if we put 5 there are only 4.

Posted by Jer on 2010-11-19 16:13:10