Wrap a string around a can and then stretch it over the diameter: it fits just over three times. This goes for any can, wheel or coin. This “just over three” is the number π. Who discovered That the outline of a circle is a little larger than three diameters was already known by the Babylonians and Egyptians almost 4 000 years ago; they used values like 3, $3\tfrac{1}{8}$ and 3,16. The first calculated π with certainty was Archimedes of Syracuse (3rd century BC): using polygons with 96 sides, he proved that π is between $3\tfrac{10}{71}$ and $3\tfrac{1}{7}$. The symbol π was used by the Welshman William Jones in 1706 and popularized by Leonhard Euler.