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Newsletter: Math Forum Internet News No. 2.39 (Sept. 29)
Posted:
Sep 29, 1997 9:26 AM


29 September 1997 Vol.2, No.39
THE MATH FORUM INTERNET NEWS
Keep Traffic Moving!  The Abacus  BEATCALC
KEEP THE TRAFFIC MOVING!
http://www.math.toronto.edu/mathnet/carcompet/carcompet.html
Everybody knows how frustrating it is to sit at a red light. Worse, a light that stays red too long can cause cars to back up, leading to gridlock. It's the traffic engineer's job to time things so that cars do not have to wait too long.
On this site, you are the traffic engineer. Through a computer simulation, you control the timings of the lights at six intersections. Each road has two lanes, one in each direction. You have measured the traffic densities and you know that traffic behavior follows a particular mathematical model (the model is described onsite).
Your task:
 decide whether traffic lights are even feasible;
 find what happens when a long light of cars is waiting at a red light and the light turns green;
 find the best light timings for three specific situations.
You are invited to try your hand at exploring mathematics in action in this real life situation. The competition was held in 1996 by the Univ. of Toronto Mathematics Network.
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THE ABACUS The Art of Calculating with Beads  Luis Fernandez
http://www.ee.ryerson.ca:8080/~elf/abacus/
All about the abacus, a calculator whose earliest known use was c. 500 B.C. in China. The abacus was used by the Japanese beginning around 1600 A.D., and excavations have revealed an Aztec abacus, c. 9001000 A.D., "where the counters were made from kernels of maize threaded through a strong that attached to a wooden frame."
Site features:
 Construction and anatomy, abacus basics  Proper finger technique  A Java applet representing the number 87,654,321  Instructions for addition and subtraction  The Abacus vs. the Electric Calculator  The Japanese, Chinese, and Aztec abacus, compared  Resources: purchase an abacus or build one out of LEGO  Abacus Museum
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BEAT THE CALCULATOR  BEATCALC!
http://jjj.mega.net/BEATCALC/
A mailing list from B. Clay. Each Monday an email message is sent to more than 4000 subscribers, with an exercise that illustrates how to do mental math computations faster than with a calculator. Learn to square numbers made up of 9's; multiply a 2digit number by 594 or 693; or divide a repeating 6digit number by 7, 11, and 13, then subtract 101... and many more.
More than 90 of these mental tricks have been archived by the Math Forum:
http://forum.swarthmore.edu/k12/mathtips/beatcalc.html
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The Math Forum ** 29 September 1997
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