Pi Formula
Pi formula relates the circumference and diameter of a circle. It can be used to calculate the value of pi if the measurements of circumference and diameter of a circle are given. Pi is a Greek letter, its symbol is π and in geometry, it is the ratio of the circumference of any circle to the diameter of that circle. In decimal form, the value of pi is approximately 3.14159... It cannot be written as an exact decimal as it has digits that go on forever. Let us learn about the pi formula with few solved examples at the end.
What is Pi Formula?
Pi, being an irrational number, cannot be expressed as a common fraction. Although fractions such as 22/7 are commonly used to approximate it, the exact value of pi, which is a nonterminating nonrepeating decimal, can be calculated using the pi formula. No matter how large or small a circle is, the circumference divided by the diameter of a circle is always π. Pi formula can be expressed as,
Pi(π) = (Circumference / Diameter)
Let us have a look at a few solved examples on the pi formula to understand the concept better.
Solved Examples Using Pi Formula

Example 1: Noah measured the perimeter of the circular section of pipe as 88 inches. Calculate the diameter of the same pipe using the pi formula. (Use π = 3.14 )
Solution:
To find: The diameter of the pipe.
The perimeter of a circular pipe = 88 inches (given)
Using pi formula,
Pi(π) = (Circumference / Diameter)
3.14 = ( 88 / Diameter)
Diameter = (88 / 3.14)
= 28.02
= 28 inches (approx).
Answer: The diameter of the pipe is 28 inches (approx).

Example 2: The diameter of a circular park measures 200 inches. How much distance have you covered if you walked exactly 1 round across its boundary? (Use π = 3.14 )
Solution:
To find: Circumference of the park.
The diameter of a park = 200 inches.
Using pi formula,
Pi(π) = (Circumference / Diameter)
3.14 = (Circumference / 200)
Circumference = (3.14 x 200) inches.
= 628 inches
Answer: Total distance walked is 628 inches.