Today's Google doodle celebrates the 30th anniversary of Pi day. Pi day, observed on the 14th of March every year, celebrates the mathematical constant Pi. Pi represents the ratio of a circumference ...

The circumference of a circle is the distance around the shape. The ability to round a number to a number of decimal places or to a number of significant figures means that answers can be written to ...

Pi is denoted by the Greek letter π. It is a mathematical constant and is approximately equal to 3.14159. It is defined as the ratio of a circle's circumference to its diameter. It was first ...