16 fun applications of the pigeonhole principle
[This article is included in the 45th Carnival of Math] Mathematical logic can produce some great trivia. Did you know that at every instant, there is a spot in the world where no wind is blowing? It is true, and the proof comes as an application of a fixed point theorem ...

3 important lessons from the financial crisis
It's hard to know what to think these days. I find myself overwhelmed sorting through all the data and predictions. It's time for reflection, so here are three of my lessons during this downturn: 1. Saving for emergencies: time to revive age old wisdom Ancient societies understood the need to save for ...

Understanding the winner’s curse
Sometimes winning comes at too high a cost. In such cases, it is the winners that are the real losers. The phenomenon is known as the "winner's curse" and it affects a wide variety of situations, from baseball free agency signings to stock market IPOs. Whether you are an executive in ...

Calculating stock or investment returns: the difference between ROI and IRR
Whether you are investing in the stock market or a business project, you need to understand rates of return. Stock gurus talk about things like ROI and IRR, but what do they mean? I'll go through the logic of each method and explain why IRR is my preferred choice. Rate of ...

How to negotiate at your job using game theory
My underpaid friend used every trick during salary negotiations to no avail. This year she got the raise she deserved. The trick that finally worked was getting sick. My friend joked the company would only realize her value after she left. By chance, it happened much sooner. My friend became very ...

Figuring out how much your time is worth–does it make sense?
Question: What's the best way to value your time? I am trying to make a decision about whether to hire help for my house. My answer: There are many ways to figure out how much your time is worth. You can get a quick estimate of your hourly rate by taking your salary ...

Game theory and the math of infinity
Many of us have a sense for physical units like 750 mL, 12 ounces, or a six-pack. But what does it mean to have an infinite size? The math is fascinating. Perhaps the most remarkable result is that infinity is not a single size. One can talk intelligently about different sizes ...