KOF (Qof ; Heb. קוף ;ק), the nineteenth letter of the Hebrew alphabet; its numerical value is 100. In the Proto-Sinaitic inscriptions its form was , which later, in the linear Phoenician script turned into . In the eighth and seventh centuries b.c.e. the kof developed as follows: the circle was opened , it turned into two half-circles , and then the left one was drawn with the downstroke without lifting the pen . The last form was preserved in the Hebrew script, while in other scripts the head of the kof formed an S, as in Phoenician (), Samaritan (), and Aramaic (). The later Aramaic and Jewish kof reduced the left curve of its head . The Nabatean script went further and the letter was written as follows: . This developed into , until it became similar to the pe (). In the Arabic script it was necessary to add diacritic marks in order to distinguish between pe () and kof ( ). See *Alphabet, Hebrew.