Hey math geeks! Check out these awesome clocks, on which each hour is marked by a either a math problem or a symbol representing a certain value.

**Math Pop Quiz Clock**

Get the conversation going the next time the MENSA meeting is at your place. Made of lightweight black metal with a matte finish Measures 11.5″ diameter Requires 1 AA Battery (not included) Easy-to-hang with “keyhole” opening on the back of the clock Work out the equations to determine the hour Fun and challenging Makes a great gift for your favorite Brainiac !

Math Pop Quiz Clock – $29.38 @ Amazon.com

**Irrational Numbers Wall Clock**

On our charmingly quirky wall clock, irrational numbers–those that can’t be represented by simple fractions–replace the usual markings of a traditional clock face. The numbers, though admittedly “irrational,” are logically arranged. For example, pi (3.14159â€¦) is just a few degrees past where a three would normally be. Mathematicians and other numerical whizzes (engineers, accountantsâ€¦anyone with a fancy calculator) will derive a virtual eternity of laughs from this clever home or office accessory. Black with white details, the 12″-diameter metal clock runs on one AA battery.

Irrational Numbers Wall Clock – $34.95 @ basbleu.com

I own a Math Pop Quiz Clock, that thing is awesome

Actually, even though you put there the most difficult equations, you can still tell the time by mere seconds. You know where the numbers should be so it is just a waste of effort. lol

In the first clock, the function for 9 is only approximate.

And the function for 7 has a second solution at -6