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Calculate Pi With a Dartboard

John Clark Craig
3 min readNov 7, 2020

You can try this at home, but do it the easy way

You have to throw a lot of darts to estimate pi
Courtesy of icon0.com on Pexels

Imagine a special, square dartboard, say exactly 2 meters by 2 meters in size, with a giant bullseye circle inscribed within its borders.

A square dartboard with inscribed circular area

If you throw darts as randomly as inhumanly possible at this dartboard, the total number of hits and misses can be used to estimate pi. But before we start throwing those darts, let’s simplify the board even more.

A Very Special Dartboard

Saw off the upper right corner of the dartboard to reduce the result to a 1 meter by 1 meter square, with a quarter of the original circle in it.

Square 1 x 1 dartboard with quarter circle inscribed

This dartboard simplifies the math, and that’s always a good thing. The area of the circular segment is a fraction of the total area of the square, and the value of pi works into the ratio. Let’s start with the formula for the area of a circle given its radius.

Do the math and you’ll see the area of the square is 1, and the area of the quarter circle part…

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John Clark Craig
John Clark Craig

Written by John Clark Craig

Author, inventor, entrepreneur — passionate about alternate energy, technology, UFOs, and how Python programming can help you hack your life.

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