monthly writings in and around mathematics by James Propp
Base two numerals can be awkward to compute with, and Roman numerals are even more awkward. But awkward is not the same as bad. Today I’ll tell you about a truly awful numeral system—possibly the very worst ever proposed as a way of doing arithmetic—but I claim that even such an abominable system is useful [ ]
“Oh, it’s just a trick thing.” – Ben Ames Williams, Coconuts Here are six puzzles, some of them classics, that don t look much alike on the surface. After stating them, I ll give a hint about what they have in common. Then I ll present solutions that all make use of the same slick trick in one [ ]
[Note to reader: This is a sequel to my widely-circulated 2021 essay “The Great Solar Bleed-Out Scam”; for the sake of readers who have forgotten or never read that earlier essay, I include it here.] April 1, 2021: Dr. Jeremiah Browne of NASA, Dr. Marissa Carson of NASA, and many other people from all over [ ]
Ask a silly question, get a silly answer. Tom Lehrer, New Math I ask too many questions. A case in point is the time I lost out on a place I wanted to rent when I asked my potential future landlord one question too many (“Does the pond have mosquitos in the summer?”). Another [ ]
A few weeks ago I was minding my own business, peacefully reading a well-written and informative article about artificial intelligence, when I was ambushed by a passage in the article that aroused my pique. That’s one of the pitfalls of knowing too much about a topic a journalist is discussing; journalists often make mistakes that [ ]
I’m a great believer in low-tech math. I don’t like to rely on things a computer tells me; what if there s a bug in the code? I prefer trusting things that I can check for myself. At the same time, I’m keenly aware of the limits of my imagination even when it’s aided by paper [ ]
As a member of the Advisory Council for the National Museum of Mathematics ( MoMath ) over the past decade, I ve had a number of unique opportunities, such as the thrilling chance to improve the Museum s datebase via my smartphone and watch exhibit-content update in real-time, and the less thrilling opportunity to break an exhibit on the [ ]
In ordinary math, the infinite decimal .999… is defined to be the limit of the terminating decimals .9, .99, .999, ; that is, it’s defined to be the real number that the fractions 9/10, 99/100, 999/1000, … approach in the ordinary sense. And that limit is most definitely 1, not some real number that’s a [ ]
This past week I was saddened to learn of the death of mathematician and teacher David C. Kelly, the founder of the Hampshire College Summer Studies in Mathematics program (HCSSiM). “Kelly”, as everyone called him, had a huge impact not just on my career but on the careers of people spanning several generations. I knew Kelly [ ]
I couldn t help but wonder Carrie Bradshaw (in every episode of Sex and the City) The best birthday party I ever had as a kid was a trip to the Museum of Natural History in New York City with half a dozen like-minded friends and my indulgent parents. The huge dinosaur skeleton in the [ ]