Zeta (uppercase Ζ, lowercase ζ; Greek: Ζήτα [ziːta] Zita) is the sixth letter of the Greek alphabet. In the system of Greek numerals it has a value of 7. Zeta has the numerical value 7 rather than 6 because the letter digamma (also called stigma as a Greek numeral) was originally in the sixth position in the alphabet. Zeta can be said to be the origin of the most common pronunciation of the Roman letter Z.