How many combinations are possible in this grid? [more inside]
posted by rahnefan on Dec 1, 2009 - 12 answers

I recently ran across a wonderful logic puzzle, but no solution was provided. I eventually worked out a complete solution myself, but it was rather ugly, and I would like to see if people smarter than me can come up with something more elegant. Are there any good Internet puzzle discussion forums floating around? [more inside]
posted by sappidus on Oct 11, 2008 - 13 answers

My geometry teacher in high school in 1984 showed us this puzzle. I was only half paying attention, but I believe the goal was to draw a line that intersected each segment only once. [more inside]
posted by mecran01 on Jan 6, 2008 - 15 answers

How do I solve this puzzle mathematically, rather than programmatically? [more inside]
posted by anomie on Sep 13, 2007 - 12 answers

What are some (easy to moderate difficulty) math problems with integer answers ranging from 0-18? I'm making mathematical seating cards where guests will solve a problem to find their table number. [more inside]
posted by Alison on Aug 30, 2007 - 25 answers

Math puzzle filter. How do you go about solving this puzzle? [more inside]
posted by batcrazy on Aug 28, 2007 - 25 answers

I am reading Douglas Coupland's new book (JPod) and I'm always a little frustrated by him. He seems to get the general vibe of nerds but is horribly off on details sometimes (in the first 50 pages, he makes reference to a "56k floppy disk"), which is agonizing. Anyway, he posits a math problem (I don't think this counts as a spoiler, I'll even omit the context and just pose the problem with page number, but if you really don't want to see anything about the book, don't read on, I guess.) [more inside]
posted by oxonium on May 27, 2006 - 42 answers

You are suspended in a large, hollow sphere. The inside of the sphere is perfectly mirrored. There is nothing else in the sphere, and all you carry is a flashlight. You turn the flashlight on. What do you see? [more inside]
posted by tweebiscuit on May 15, 2006 - 41 answers

A crystal consists of 100,000,000 layers of atoms such that there is 1 atom in the first layer, 3 in the second, 6 in the third, 10 in the fourth, 15 in the fifth, and so forth. Exactly how many atoms are there in the entire crystal? [more inside]
posted by Kwantsar on Oct 8, 2005 - 8 answers

The top of this little sign says, "This compressed message [from the NAIC-Arecibo Observatory] is a mathematical puzzle for an intelligent species to solve. The answer will reveal information about the Earth and its people." I got nothin'. Help?
posted by gleuschk on Jul 28, 2005 - 17 answers

The management of my office building is holding a contest: determine the number of jelly beans in a container. Prize: $500 at Best Buy and all the beans. [more inside]
posted by smcniven on Mar 22, 2005 - 12 answers

Can anyone settle a 15 year old argument for me? It turned into one of those things "we don't talk about" but it's always bugged me. The question is simple and involves three points and a circle - more inside. [more inside]
posted by twine42 on Dec 14, 2003 - 19 answers