Quick: What's 19 2...without your calculator? (361.) Squaring complex, two-digit numbers in your head isn't that difficult if you know a simple trick, according to the Secrets of Mental Math author ...

Squaring a number simply means multiplying the number by itself. As an example, if you are calculating a two-year compound growth factor for your business, you multiply the one-year growth rate by ...

Everyone gets really wow'd when someone pulls off some exceptional mental math. The best part is, you can totally be that guy at the party with a little practice and preparation. What follows is 10 ...