pi is a letter of the Greek alphabet and predates its use in mathematics. pi is a letter of the Greek alphabet and predates its use in mathematics. pi is a letter of the Greek alphabet and predates its use in mathematics. pi is a letter of the Greek alphabet and predates its use in mathematics.

the symbol is from ancient greece. it is a letter of the alphabet and since much of our modern mathematics is based on the greek, we use many of their symbols

That's pi, the sixteenth letter of the Greek alphabet. In mathematics, it is defined as the numerical value of the ratio of the circumference of a circle to its diameter.