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Buffon’s Needle

probability
monte-carlo
visualization
Estimate the value of π using Buffon’s needle problem - a classic probability experiment that connects geometry with randomness.
Published

January 1, 2025

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Results

Total Needles: -
Line Crossings: -
π Estimate: -
True π: -
Absolute Error: -
Standard Error: -

About This App

Buffon’s Needle is a classic problem in geometric probability, first posed by Georges-Louis Leclerc, Comte de Buffon, in the 18th century. The problem involves dropping needles on a floor made of parallel strips and counting how many needles cross the lines between the strips.

This simple physical experiment can be used to estimate π! The probability that a needle of length \(\ell\) will cross a line when dropped on a floor with parallel lines spaced \(d\) apart (where \(\ell \leq d\)) is:

\[P = \frac{2\ell}{\pi d}\]

By rearranging this formula and using the Law of Large Numbers, we can estimate π by performing many trials:

\[\pi \approx \frac{2\ell \cdot n}{d \cdot c}\]

where \(n\) is the total number of needles dropped and \(c\) is the number that cross a line.

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Copyright 2025, Apurva Nakade