Leonhard Euler used the symbol pi in 1737.
Maurits Escher was a remarkable Swiss mathematician and teacher that was responsible for instituting the use of the symbol pi in mathematical notation.
Lindemann
Mr. Euler
Leonhard Euler.
Leonhard Euler.
It was the mathematician William Jones who first used pi as a mathematical symbol in 1706
Leonhard Euler.
Leonard Euler
Mathematician Rudolph Swetchefriz{Added} The symbol is not "for" pi but is pi - one of the letters of the Greek alphabet.
Leonard Euler
The first known use of the symbol π to represent the mathematical constant approximately equal to 3.14159... was by Welsh mathematician William Jones in 1706. However, it was the Swiss mathematician Leonhard Euler who popularized the use of π in his mathematical works and made it widely recognized.
Leonhard Euler