A painting showing Archimedes at work The Greek mathematician, physicist, astronomer and inventor Archimedes (c. 287–212 BC) was one of the greatest scientists of the classical age. Born in Syracuse in Sicily, he spent most of his life there, although as a young man he furthered his education in Alexandria, Egypt. Among many inventions and mathematical advances, Archimedes calculated an accurate estimate of *π* (pi), the ratio between a circle's diameter and its circumference (edge). He stated it as a fraction, 22/7, which in decimal figures is about 3.14. Pi is used today in many areas of mathematics, science and engineering to measure the lengths of arcs and curves, the areas of curved surfaces and the volumes of many solids. Archimedes also came up with a mathematical law ("Archimedes' Principle") which states that a body immersed in a fluid experiences a buoyant force equal to the weight of the fluid it displaces (pushes aside).

**Archimedes**

# Archimedes

## The size of the Universe

Archimedes also developed a way of carrying out calculations with huge numbers, partly to investigate how many grains of sand would fit into the Universe. He suggested that a "myriad" (from the Greek word for infinity) could stand for 10,000, and then proposed a number system using a myriad myriads, or 100 million. This work suggested for the first time the enormous scale of our Universe.

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