7 Math Tricks That'll Make Your Life Easier

Pixabay via Google ImagesThe worst part of going out to dinner with a group of friends is figuring out who owes what at the end of the night. All too often, once everyone's chipped in, there's either not enough money on the table, or way too much.

When trying to plan for retirement, or figure out whether or not to make an investment, one helpful thing to know is how long it will take to double your initial capital.

And when you're considering taking a new job with an annual salary, it might be useful to know how that salary compares to what you'd earn at a job with an hourly pay rate.

What all these things have in common is that there are handy math tricks that can let you figure them them out quickly and without having to resort to pulling out the calculator on your phone. We've assembled seven such tricks, and talk a little about how they all work.

Eric Platt and Walt Hickey contributed to earlier versions of this article.