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 ...

Interest is the amount of money you must pay to borrow money in addition to the loan's principal. It's also the amount you are paid over time when you deposit money in a savings account or certificate ...