- 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?