You know those people who somehow manage to pull the day of the week out of thin air, past or present, no matter how far off a date is? As it turns ou ...

How to Auto Populate the Date in Excel. When you're setting up a Microsoft Excel spreadsheet that contains date information, you'll speed your task if you let Excel do the tedious work of filling ...

This reminded me of modular arithmetic and the formula for calculating the day of the week for any date in history. We use modular arithmetic all the time.