Kara and I are hosting a mental_floss session (Trivia! Puzzles! Prizes!) next Thursday at the "End of Time" Mensa American Gathering in Reno. Today's mentalfloss.com Brain Game Think Thursday challenge just might be a Mensa-worthy puzzle. Good luck!

What's the missing number in the following set, and why?

1, 2, 1, 1, 1, 1, ?, 2, 9, 3, 8, 4, 7, 5, 6

Here is the ANSWER.

THE ANSWER:

0 (zero).

The numbers represent the digits on an analog clock face, from top to bottom and left to right:

Thanks for playing! Tomorrow, it's Free-for-all Friday.