is among the oldest and most famous constant of mathematics, however as a number it wasn’t called until the early 18th century.
Before was known as the number defined as the circumference of a circle divided by its diameter. However, in 1706 self taught mathematics teach William Jones labeled the constant in his book “Synopsis Palmariorum Matheseos” (a new introduction to mathematics). Perhaps he named it this because was Greek for p which would be first letter of the word periphery.
This notation was then popularized by the famous Swiss mathematician, Leonhard Euler in 1738, two decades after ‘s official naming.
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