Mathemagic
by Raymond Blum · first published 1991
2mentions
2recommended by
2HN commenters
2011–2021first – last mentioned
100% recommend
Dozens of number tricks from easy to expert.
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When I was a kid, I loved the Mathemagic book [1] IIRC this was one of the tricks described in the book. [1] https://www.amazon.com/Mathemagic-Raymond-Blum/dp/0806983558
on “The Party Math Trick” ↗People sometimes guffaw at this, but I can't recommend Donald Duck in Mathemagic Land enough: http://www.youtube.com/watch?v=iEVGQKwKeCc They skip over several centuries of shifting and tweaking between the triad and the modern (western) major scale, but it's a great visual answer…
on “Music Theory for Beginners” ↗