Scientists have calculated pi to 105 trillion digits, although most of us are more familiar with the approximation 3.14. But how do we know that pi is an irrational number?

BOISE, Idaho — National Pi Day is celebrated each year on March 14, as it represents the first three digits of the mathematical constant 3.14, and falls on Albert Einstein's birthday. It is also ...

It is not possible to write Pi day using that format, but it is easy to write Pi approximation day. In China and many other countries in south-east Asia, dates are written year/month/day.

Scientists have calculated pi to 105 trillion digits, although most of us are more familiar with the approximation 3.14. But how do we know that pi is an irrational number?