Isopsephy

Isopsephy is the ancient Greek practice of adding up the numerical values of the letters in a word, since the Greeks used their alphabet to write numbers. Two words with the same sum were considered linked. It left traces in graffiti at Pompeii and in Christian tradition: the number 666 in the Book of Revelation is often read through this kind of calculation, in Greek or in Hebrew, although the identity of the name it refers to remains debated. It is the Greek counterpart of Hebrew gematria.