There is no such letter because there is no interval between pi and pi.
PI is the Latin name of the Greek letter(by Greek letter I mean the PI symbol.
The Greek capital letter for Pi is Π.
The term pi comes from the greek letter pi, which is the first letter of the word which in English is "perimeter".
The Greek word for perimeter begins with the letter pi, and since circumference and perimeter are the same the letter Pi was used.
Pi is a Greek letter for the "P" sound.
The letter Pi (π) is capitalized to Π
Pi is a letter of the Greek alphabet.
The letter before Pi is Omicron reprsented by 'O' in caps and 'o' in small case.
Pi is the sixteenth letter of the Greek alphabet.Π,π
The letter between pi and sigma in the Greek alphabet is rho.
The value for Pi for math is 3.14. Pi is the 16th letter in the Greek alphabet.