Skip to main content
Concord Academy

Enigma Math Club


Each Wednesday from 6:00 PM to 7:00 PM we meet on the 1st floor of CA Labs to prepare for math competitions, enjoy some recreational mathematics, or work on logic puzzles.  Everyone is welcome to attend every week or just once if you want to check it out.




Student Officers:

Nora Zhou, Eliana Knight, and Jason He.


Faculty or Staff Advisors:

Shawn Bartok


Recent work:

We attended the Harvard MIT Math Tournament in November and are currently preparing for the AMC as well as a scavenger hunt we plan to host for the school.  Please email any of the faculty advisor(s) or cohead(s) with questions or for more information.



List of summer math camps US​ (word doc)​​​

List of summer math camps in US (pdf)


Current Problem of the Fortnight:

Alice and Bob decide to play the game, “I’m thinking of a number between 1 and 100, what is it?”

Alice is thinking of a number between 1 and 100 and it must be a whole number.  Bob gets to ask yes-or-no questions, e.g. is your number bigger than 80?  Bob wants to ask the fewest possible questions before figuring out Alice’s number.

Part A:  If Alice always tells the truth, then how many questions are necessary for Bob to always figure out her number?  You want a strategy that makes this number as small as possible and doesn’t rely on luck.

Part B:  If Alice is allowed to lie once, then how many questions must Bob ask?

Part C:  If Alice is thinking of a number between 1 and N, then how many questions must Bob ask if she is allowed to lie once?

Solutions and partial solutions are due by 3:15 PM on 5/9.  See Shawn with questions.