NPR's Ailsa Chang speaks to mathematician Eugenia Cheng about the Pascaline -- a 17th-century invention credited as the first mechanical calculator.

Here’s how the Rule of 72 works: Divide 72 by your expected annual interest rate (as a percentage, not a decimal). The answer is roughly the number of years it will take for your money to double. For ...

The Rule of 72 is a simple calculation tool for investors to use, but it's not necessarily the most accurate. Here are some ...

More than 110 leaders will speak at a United Nations climate summit on Wednesday. They aim to strengthen plans to reduce ...

If you’ve ever traveled abroad to a place where the local currency is much different in value from the U.S. dollar, you’ve probably found yourself scrambling to calculate the differences in price when ...

Disposable batteries seem so 1990s. Sure, it’s nice to be able to spend a couple of bucks at the drugstore and get a flashlight or TV remote back in the game, but when the device is a daily ...

Check the currency rates against all the world currencies here. The currency converter below is easy to use and the currency rates are updated frequently. This is very much needed given the extreme ...