Knowing how to partition numbers and number bonds can make addition easier. It can even help you to work out the answer in your head. Test out your knowledge of adding 3-digit and 1-digit numbers ...

In many parts of the US, it has long been possible to make local calls with just the seven-digit phone number; the three-digit area code was implicit for calls between numbers using the same area ...

If you haven't noticed, each country has a different length of phone number, but there is a reason it's done that way. Here's ...