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Ambiguous PIN Code (Posted on 2010-11-17) Difficulty: 3 of 5
Susan couldn't quite remember her bank PIN code.

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?

See The Solution Submitted by Charlie    
Rating: 2.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: Possible solution | Comment 6 of 8 |
(In reply to Possible solution by broll)

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

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