Time for a challenge! Here, the riddle is encoded using a specific cipher. You must decode the numbers and answer the riddle correctly to solve it. Good luck!


Note: I will start adding bounties to my riddles, should they continue to be unsolved. That way you all get rewarded for your achievements.

  • $\begingroup$ +1 for the note $\endgroup$ Commented Dec 10, 2018 at 2:59

2 Answers 2



You are using an unmodified prime numbers cipher. Every two digits make up a prime number. Each pair's place in the prime set corresponds to its alphabetical rank. This allows us to learn that your code reads "When is a mask not a mask?"


There are a few possible responses to this riddle and we lack the context to know which one is desired. A few possibilities could include:

- When it is in plain sight
- When it is used as a numerical limit
- When it reveals the wearer's true face
- When it is a sheet mask (in cosmetology)
there might be more, but this was off the top of my head

  • $\begingroup$ sniped by a couple of seconds ;) $\endgroup$
    – NL628
    Commented Dec 10, 2018 at 2:21
  • $\begingroup$ @arpeyji You solved the cipher correctly, however, the answers presented are incorrect. Keep trying though! $\endgroup$ Commented Dec 13, 2018 at 21:17
  • $\begingroup$ @EdwardNigma It seems that you have changed your mind about the solution to this riddle? You initially indicated that Arpeyji had solved it, but now you seem to be indicating that the solution is incorrect. Can you clarify? $\endgroup$ Commented Dec 18, 2018 at 21:13
  • $\begingroup$ I had misread the solutions haha At the time, I had been very busy and read through his answers quickly, rather than take time to read them. So, in my mind, he had the correct answer. Upon further review, however, he had the wrong answer. So, it was indeed my own fault. I apologize for the situation. $\endgroup$ Commented Dec 18, 2018 at 22:29

Based on the riddle found by @Arpeyji

Are you asking:

When is a mask ("anything that disguises or conceals; disguise; pretense:")
not a mask ("a covering for all or part of the face, worn to conceal one's identity.")

If so, I would answer with something like:

A subnet mask

  • $\begingroup$ Incorrect, though I do like your logical reasoning. ;) $\endgroup$ Commented Dec 14, 2018 at 23:00

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