For laptops, MacBooks and desktop PCs, good audio can often seem like an afterthought. It’s hard to get quality sound from built-in speakers, which have to be crammed inside a hyper-thin chassis ...

The original version of this story appeared in Quanta Magazine. Imagine that someone gives you a list of five numbers: 1, 6, 21, 107, and—wait for it—47,176,870. Can you guess what comes next? If ...