James Tanton
@jamestanton
An Aussie fellow promoting uplifting joyful genuine math thinking and doing for students & teachers alike. Thrilled: https://t.co/1MUZpXFold reaching millions!
ID:100076513
http://www.gdaymath.com 28-12-2009 23:28:57
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Sunil Singh James Tanton describes Exploding Dots as a way to visualize long division, not a replacement. Once you understand it, you realize it's the same thing as long division and can use the simpler, standard algorithm with confidence.
gdaymath.com/lessons/explod…
Following David Marain Fred G. Harwood
Call N 'sandwiched' if N-1 and N+1 are both prime numbers.
a) If N>4 is sandwiched, then N is a multiple of 2x3=6. Why?
b) If N and 2N are each sandwiched, then N is a multiple of 2x3x5=30. Why?
c) If N, 2N, and 3N each each sandwiched, then N is a