I call it the * Factorial Watch*. It will certainly appeal to mathematics geeks, but should also interest anyone who appreciates a unique and creative time-telling experience.

But first–What’s a factorial??? Wikipedia online defines it as: “The non-negative integer which is the product of all integers less than or equal to itself.” It takes the symbol **n!**, where** n** is the non-negative integer. For example:

**n!**

1! = 1

2! = 2 x 1 = 2

3! = 3 x 2 x 1 = 6

4! = 4 x 3 x 2 x 1 = 24

5! = 5 x 4 x 3 x 2 x 1 = 120, and so on.

Now let’s apply this concept to time-telling. The watch design is illustrated below, in two sizes and dial colors, to illustrate the factorial concept. Two different times are presented.

** TIME: 11:39 TIME: 9:47**

men’s size (50mm x 40mm) women’s size (40mm x 35mm)

Two series of numbers are displayed in vertical succession. **Each number represents the factorial of that number.** The left side of the dial indicates hours (or month of the year in the date mode); the right side indicates minutes (or day of the month in the date mode). Both sides are separated by the factorial symbol (!).

Starting from the top, each displayed number (actually the factorial) adds to the one below it. Since no hour is greater than 12, no number on the left side is greater than 3. Since no minute is greater than 59, no number on the right side is greater than 4. **It may seem tedious to calculate at first, but once the wearer becomes familiar with the factorial of numbers 1-4, time-telling becomes quick and easy, and a lot of fun.** And very puzzling to the onlooker, who does not have the “key” to the solution. I really love the idea, and it makes you **think** the time, not just **read** it.

The watch case can be done in black or white, with matching leather strap. The dial can be done in one of a palette of colors—red, blue, green, yellow, orange, etc.—with matching stitching on the leather strap. It would have an LCD display and be constantly lit, to allow time for calculating. (LED requires more energy, and would reduce battery life.)