Tinkle Explains
Happy Pi Day!
Writer: Shreya Ghosh
Illustrator: Narendra Pardhi

While studying Maths, you might have come across something quite interesting, setting itself apart from the usual “boring Maths” notion. This interesting thing is actually a number with an equally unique name: pi. It is denoted as π and its value is 22/7, roughly 3.14.

Yes, Shambu, there might just be some correlation between those two things. Pies are circular. The number pi has an important relation to a circle. If you divide the circumference of a circle (the measurement of its outside) by its diameter (the line that runs between two ends of a circle, through the centre), you get the number known as pi. 

By constant, it means that the value of pi does not change. Speaking of pi’s value, it has an interesting backstory. For a long time, humans have tried to arrive at its value. The number has been known for about 4000 years. Calculations of the area of a circle by ancient Babylonians give a value of 3 for pi, and the formula used by the ancient Egyptians yields around 3.1605. Later, legendary mathematicians like Archimedes of Syracuse (who first calculated the value of pi, and also famously said “Eureka!”), Zu Chongzhi of China (429-500 AD), William Jones of Wales (1675–1749), Leonhard Euler of Switzerland (1707-1783), and Georges Buffon of France (1707-1788) also contributed to the knowledge of this number.

There are different types of numbers. All numbers such as 1, 2, 3, and so on, are “natural numbers”. Add zero to the mix and you get a group called “whole numbers”. Enter fractions: those are part of a group called “rational numbers”. Which kind do you think pi is?

To understand the different types of numbers and how they relate to each other, look at this venn diagram:

Pi falls in the ‘irrational’ circle. This means that after the decimal point, the digits never really end. They keep going infinitely! The value of pi up to 10 decimal places is 3.1415926535. Can you memorize this? Challenge your friends too!

So, why celebrate pi day? It is a day for maths lovers to celebrate all the things that make the subject magical! Interestingly, this day is celebrated on the 14th of March because when written in the month/date format, this date becomes 3/14. These are also the first three digits of, you guessed it, pi! See? Magic. Happy Pi Day, one and all!

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