Thursday, October 30, 2014

Illustrated Riddles from Open University

Some fun illustrated riddles and insight on problem-solving.

Wednesday, September 22, 2010

The Cosmic Number

four is cosmic
4 is cosmic.

1 is 3, 3 is 5, 5 is 4, and 4 is cosmic.
8 is 5, 5 is 4, and 4 is cosmic.
2 is 3, 3 is 5, 5 is 4, and 4 is cosmic.
15 is 7, 7 is 5, 5 is 4, and 4 is cosmic
9 is 4 and 4 is cosmic.
18 is 8, 8 is 5, 5 is 4, and 4 is cosmic.
17 is 9, 9 is 4, and 4 is cosmic. 
100 is 10, 10 is 3, 3 is 5, 5 is 4, and 4 is cosmic.

If you think you recognize the pattern, submit an example.  If you need more examples, I can give you more.

Thursday, September 16, 2010

Running Out of Riddles

Well I thought I could make it a whole year providing a new riddle every week, but it appears I am almost out.  I will continue posting puzzles as I find them, but I can't guarantee a weekly riddle any more at this point.  For now, an old one my dad once told me:

What did the left eye say to the right eye?

Tuesday, September 7, 2010

The Hateful Neighbors

The Boggis, Bunce, and Bean families were once united in their pursuit of a common enemy, but have since developed a bitter and irreconcilable hatred for one another.  Each family lives in its own house in its own part of town, and all is well and good, so long as members of different families don't cross paths - if they do, they will start brawling until the poor sheriff has to come out and break them up.  They are very civil indoors, however. 

Each family needs to be able to access the post office, the general store, and the sheriff's office without encountering members of other families.

So the sheriff has come up with a great plan; draw up plans for each family to have its own three paths, traveling from each home to a each of the three municipal buildings.  In this way, for example, the Boggis family has three paths, where each path leads from its front door to the front doors of the post office, general store, and sheriff's office.  Can he do this without letting the paths cross, and without digging any tunnels or building any bridges - in other words, working in a two-dimensional plane?

Wednesday, August 25, 2010

1000 Bottles of Wine

Borrowed from
You are the ruler of a medieval empire and you are about to have a celebration tomorrow. The celebration is the most important party you have ever hosted. You've got 1000 bottles of wine you were planning to open for the celebration, but you find out that one of them is poisoned.
The poison exhibits no symptoms until death. Death occurs within ten to twenty hours after consuming even the minutest amount of poison.

You have over a thousand paid caterers to help with the testing and just under 24 hours to determine which single bottle is poisoned.

You have a handful of prisoners about to be executed, and it would mar your celebration to have anyone else killed.

What is the smallest number of prisoners you must have to drink from the bottles to be absolutely sure to find the poisoned bottle within 24 hours?

Wednesday, August 18, 2010


One time in college I emailed my dad asking for money and he said I could have some if I solved the following equation:


Each letter represents its own digit (0-9) and multiple occurrences of the same letter represent the same digit (eg if one of the E's represents a 3, they all do).

Friday, August 13, 2010

A Boat in a Tank

Imagine you are in a small rowboat floating in a swimming pool.  There's a big rock in the boat and you drop it overboard. Does the water level rise or fall?  Why?