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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: A Pin that works | Comment 4 of 9 |
(In reply to A Pin that works by Jer)

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

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