Marin Math Circle

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Starting in September 2009!

The Marin Math Circle brings together students who are interested in exploring new mathematical topics and challenging problems. Although math circles have existed in Europe for decades, and in other Bay Area cities for years, the Marin Math Circle is brand new, starting in September, 2009.

The Marin Math Circle is open to students in grades 6-8. We will meet Wednesdays from 6:30-8:00 at Dominican University of California, in San Rafael.

Come join us for puzzles like the ones below! Want to see more cool problems?

1) There are 100 light switches on the wall, all turned off. A hundred toddlers come by. The first toddler flips every switch. Then the second toddler flips just switches 2, 4, 6, 8, ... etc. Then the third toddler flips switches 3, 6, 9, 12, ... etc. This pattern continues until finally the 100th toddler flips just switch number 100. How may lights are turned on at the end?

2) What is the maximum number of pieces you can divide a watermelon into with four straight cuts, if you are NOT allowed to rearrange the pieces between cuts? With five cuts?