Pi is defined as the ratio of the circumference of a circle to the diameter that is approximately equal to 3.14159. In a circle, if you divide the circumference (is the total distance around the circle) by the diameter, you will get exactly the same number. Whether the circle is big or small, the value of pi remains the same. The symbol of Pi is denoted by **π** and pronounced as “pie”. It is the 16th letter of the Greek alphabet and used to represent a mathematical constant.

Pi is also known as an irrational number which means that the digits after decimal point never end being a non-terminating value. Therefore, 22/7 is used for everyday calculations. **π** is not equal to the ratio of any two number which makes it an irrational number.

How to calculate value of Pi?

\(\large \pi= \frac{circumference}{Diameter}\)

π = 3.14159

Let us understand the concept of Pi with the following a few examples.

Lets have a look at first 100 decimal places of Pi

3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 7067

Examples

**Question – **A boy walks around a circle which has a diameter of 100 m, how far the boy has walked?

Solution:

Distance walked = Circumference

Circumference = π × 100m = 314.159 m

Therefore, circumference = 3.14m

**Question** – Calculate the circumference of the circle.

Solution:

We know that the Circumference of a circle is the distance around a circle.

The Circumference formula is given by c = π x d.

Therefore, when substitute the value of d, we get;

C = π x 18

= 56.2

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**Practise This Question**