# Department of Mathematics

The Enzo of the Department of Mathematics is dedicated to one of the most important numbers in mathematics, the number Pi. It appears in all areas of mathematics, and in many other sciences.

The number Pi, is the surface area of a disc of radius 1, or half of the length of the perimeter of a circle of radius 1.

Fascination with Pi has motivated many mathematical discoveries from the Babylonians right up to today. The ancient Greek problem of squaring the circle" (finding, using a ruler and a compass, a square with the same area as a given circle) was only solved in 1880 by Ferdinand von Lindemann, who finally proved that it was impossible.

Pi is an irrational number, which means that its decimal goes on forever without repeating.The decimal expansion of Pi, and other approximations to Pi, also have a very long history. Archimedes invented groundbreaking methods in order to find the first good approximations. Since then many formulas have developed to compute more and more digits. The current record of calculating Pi is held by the American Alexander Yee and his partner Shigern Kondo. They calculated Pi to 12'100'000'000'050 decimal places.

#### Memorising Pi

The record for memorising Pi was achieved by the Chinese Chao Lu who recited Pi from memory to 67’890 places. The attempt lasted 24 hours and 4 minutes.

#### Places of Pi

See the first 1’000’000 places of Pi here:
http://www.pi-zahl.de/#Pi-mit-1-millionen-stellen-hinterm-komma

Website: www.math.ethz.ch

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