One simple rule can help solve any complex equation. Here's a hint: all it takes is a catchy acronym.

Get out your timer and number two pencil to see if your arithmetic skills from grade school are still intact.

There are probably a lot of things you learned in school that you don’t even remember, but the “order of operations”—also known as PEMDAS—is likely to be one that stuck with you; you’ll mess up even ...