My Best Mathematical and Logic Puzzles

"I actually couldn’t find my copy, but I have a similar book. Basically, it’s a stand-in for any book by Martin Gardner . He is a superhero, a rockstar in the puzzle world. He was a columnist for Scientific American for decades. When you talk to puzzlers and mathematicians, it’s shocking the number of them who say that they fell in love with this area because of Martin Gardner’s columns. He would present what he called ‘recreational’ mathematics to show that math is not boring. Math can be fun. They’re logic puzzles, mostly. What I love about them is they’re the kind of puzzles where when you figure out the answer (or, often, read the answer, because I don’t get them all) you’re like, ‘Oh, yes, of course!’ It’s that feeling of, ‘I should have gotten that. I can’t believe I didn’t see that!’ That is a wonderful feeling. “Doing puzzles is like going to the mental gym” I’ll give you one example. There are two kids on bicycles and they’re 20 miles apart. They’re pedaling towards each other at 10 miles an hour. There’s a fly on the handlebar of one of the bikes that flies towards the other bike at 15 miles per hour. As soon as it hits the handlebars of the other bike, it flies back to the first one and keeps going, back and forth. The question is, ‘What distance does the fly fly in the time it takes for the bikes to reach each other?’ And when you first hear that, you’re like, ‘oh my God, that’s so complicated. How would I ever figure that out?’ The default method of solving it is to try to figure out how far the fly went on that first trip, then on the second trip and so on, and then to add them all together. That’s a super complicated mathematical calculation, summing an infinite series. But what I love is that if you step back for a second and say, ‘Wait. What are we really asking here? Is there a simple way of working this out?’ the answer is yes. Because what you’re figuring out is how far the fly flies in the time it takes the two bikes to hit each other. And that’s pretty easy. The bikes are 20 miles apart, they’re each going 10 miles an hour so it will take them an hour to reach each other. How many miles does a fly go in an hour, if it’s going 15 miles an hour? 15. So it’s super simple once you see it. But when you are first presented with it, you’re like, ‘What the hell?’ That is a lesson I try to take to real life. What is the real problem? Don’t just dive in and start trying to go with your first instinct. Step back and say, ‘What am I really trying to accomplish here?’ Yes, absolutely. If you write a puzzle book without answers, you’re going to get into trouble. I write about this in my book. Back in the day, they did not provide answers in puzzle books. The most famous riddles of the Middle Ages are in a 10th-century book called the Exeter Book . It has about 95 riddles written by monks and there are no answers. A millennium later, there are still academics debating these riddles. ‘The answer is a team of horses.’ ‘No, it’s a candle.’ ‘No, it’s a bucket.’ They’re writing papers, going to conferences. I love that. Some could say it’s one of the greatest wastes of human mental energy ever, but I prefer to see it as a noble pursuit."