What is Pi?
Pi is an irrational number, this means it goes on and on, it has an infinite amount of numbers after the decimal point and it never repeats the same pattern. By definition, it is ‘the ratio of the circumference of a circle to its diameter.’ Pi is always the same number, no matter what the size of the circle you’re measuring is.
Brief History of Pi
Pi is a very old number. We know that the ancient Egyptians and the Babylonians knew about the existence of the ratio of pi, although they didn’t know its value as we do today. They had figured it was a bit bigger than 3, the Babylonians thought of Pi’s value as 3.125 and the Egyptians had a worse approximation of about 3.160484.
The modern symbol for Pi, π, was first used in 1706 by William Jones, an English mathematician. It is an ancient Greek letter and was chosen to represent the number 3.141592... because the letter π, in Greek, is pronounced like our letter ‘p’ and stands for perimeter( Pi is used to calculate many things; one of which is the perimeter of a circle).
In the 1800’s, people sat down for years on end to try to find the values of Pi, they didn’t have calculators to use and wrote everything they found out by hand.
Facts about Pi
Many mathematicians have tried and failed to prove that Pi repeats its pattern at some point. In fact, in 1768, Jonathan Lambert proved that there cannot be any repeating pattern in the number Pi. One thing that is certain is that we’ll never know all the digits of Pi.
Pi day is celebrated on the 14th March, because Americans write the date the opposite way to us, for example, the 14th March 2011 would be written 3.14.2011, which is 3.14, the first three digits of Pi.
To work out the area of a circle, you multiply Pi by the radius². For this example, let’s say the radius is 3cm.
Area=πR² = πx9= 28.2743... cm²
To work out the circumference, you use the formula circumference= 2πR. For this example, the radius is 5cm.