The Triangular Binary Clock

  • 1 III. Physikalisches Institut B, RWTH Aachen University


A new idea for a binary clock is presented. It displays the time using a triangular array of 15 lamps each representing a certain amount of time. It is shown that such a geometric, triangular arrangement is only possible because our system of time divisions is based on a sexagesimal system in which the num- ber of minutes in 12 hours equals the factorial of a natural number (720 = 6!). An interactive applet allows one to “play” with the clock.

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  • [1] Pretz, J. “A different way to read o the time - A new idea for a binary clock”, Journal of Recreational Mathematics, Vol. 35(4), 327{330, arXiv:1006.1373v1 [math.HO], 2006.

  • [2] Neugebauer, O. The Exact Sciences in Antiquity, Barnes & Noble, New York, 1993.

  • [3] Wikipedia article. “Babylonia”:

  • [4] Richard A., Carrigan, Jr. “Decimal time”, American Scientist, 305(78), 66, 1978.

  • [5] Wikipedia article. “Decimal time”:


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Recreational Mathematics Magazine is a journal for mathematicians who enjoy imaginative ideas, non-standard approaches, and surprising procedures. The journal addresses such topics as: games and puzzles, problems, mathmagic, mathematics and arts, math and fun with algorithms.