Join schools from right across the country as we attempt to find an approximation for Pi – by dropping things!

In 1777, Frenchman Louis Leclerc, also known as the Count of Buffon, created an experiment that would produce an approximate value for Pi. Buffon worked out that by randomly dropping needles onto a page with parallel lines drawn on, the probability that a needle would cross one of the lines was related to pi.

The Buffon’s Needle experiment uses a large sheet of paper (we recommend A3) and a few sticks (these ones are ideal). Make sure that your sticks are all the same length.

Draw parallel lines down your paper. The gap between the lines is important – it must be twice the length of the sticks. So with 4.3cm sticks, the gap between the lines should be 8.6cm.

Drop the sticks onto the paper, and record:
a how many sticks are on the paper, and
b how many of them are touching or crossing a line.

Dividing a by b will give us an approximation to pi. 

There’s a full demonstration in the video below.

Once you’ve got your results, submit them using this Google form. You can submit results individually, or add up the numbers for your class or school and send them all at once. The bigger the sample size, the closer to Pi the result should be, so we’ll total up all the results and see how close we can get.

Watch this space for the results!