On April 16, 2015, Tanya Khovanova wrote in her blog:
Here is my new logic puzzle.
I thought of a positive integer that is below 100 and is divisible by 7. In addition to the public knowledge above, I privately tell the units digit of my number to Alice and the tens digit to Bob. Alice and Bob are very logical people, but their conversation might seem strange:
Alice: You do not know Tanya’s number.
Bob: I know Tanya’s number.
What is my number?
(In reply to re(4): could be
By the same or similar logic, it is possible that Alice is a Liar from the land of Liars and Knights and Bob does know Tanya's number.
What might be noted is that Tanya composed her blog entry and puzzle on Foursquare day (of the previous year, 2015). One can Google-search and find that there indeed exists a math blog composed by a Tanya Khovanova for which this puzzle is mentioned. Posts on that blog regarding to the solution and logic to the puzzle are similar to those that have already been posted earlier. It is not clear what Ady is asking for, though.
Posted by Dej Mar
on 2016-05-11 18:29:18