One of the many features of Excel is being nosy. That's right, you can quickly calculate a persons age as long as you have their birth date.

To calculate the age, the DATEDIF function, set to check year, determines the number of years between the date in the DOB cell and the current date.

Percentages aren't always easy to calculate, but one of the best tools in Excel's toolbox is calculating percentages for you. Here's how to do it.