A lily pad doubles in size every day. On day 30, it covers the entire lake. On what day did it cover half the lake?

Why this works

At first glance, this riddle seems to dance around in a way that makes it feel almost enchanting, yet deceptively simple. The key lies in understanding the exponential growth of the lily pad, which doubles in size each day. This means that if the entire lake is covered on day 30, it must have covered half of the lake the day before, on day 29. It’s a classic case of exponential growth, where the solution is hidden in the rhythm of the doubling rather than a linear progression of days. This riddle beautifully illustrates how our intuition can sometimes lead us astray. We often think linearly, assuming that coverage increases steadily, but here, the lily pad's growth is exponential—a concept that can be mind-bending. The "aha moment" comes when you realize that each day is not just a single increment of growth, but rather a twofold leap forward, making day 29 the unsung hero of the lake's gradual transformation. Interestingly, this riddle is a great conversation starter about the nature of exponential growth, which is not only a mathematical concept but also prevalent in areas such as technology and finance. For instance, the way data storage capacity has exponentially increased over the last few decades mirrors the lily pad's doubling. So next time you encounter something that seems to grow slowly at first, remember it might just be waiting for its moment to bloom!