Windows 7 users will find the built-in calculator app has received a very nice overhaul which includes some new – and useful – date calculation features. In the standard calculator, click on the View menu and choose the Date Calculation option to display the worksheet you see here.
You now have several different date calculation options to choose from using the drop-down option in the worksheet. Here I’m calculating the difference between two dates. You can also add/subtract days to a specific date which can be an easy way to get an approximate birth date.