After the third trick, the victim finds an excuse to leave the room. His reaction is understandable. Most card magic is a crashing bore, unless it is performed by skillful professionals.

With card magic, I know enough to be able to combine principles ... flipped over and exactly which ones — number and suit — are not. And yet, the math behind the trick isn’t always the hard part.

The answer, travelers find, can take some math. Travelers say differences in ... pays $550 for his Chase Sapphire Reserve card and says he has found high prices on Chase’s travel portal, such ...