The twenty two letters of the Hebrew alphabet carry fixed numeric values in their traditional order: the first nine letters, Aleph through Tet, run 1 to 9; the next nine, Yod through Tzadi, run 10 to 90 in steps of ten; and the final four, Kof through Tav, run 100 to 400 in steps of one hundred. Five letters take a different shape when they end a word, the final or sofit forms, and some systems extend the table for these to 500 through 900 rather than reusing the values of their ordinary forms, a choice that produces different totals for the same word depending on which convention a given calculation follows.
Mispar hechrachi, standard value, is simply the sum of a word's letters read this way, and it is the technique behind gematria's best known results, including the frequently cited equivalence of the word chai, life, with the number eighteen, which is why multiples of eighteen became a customary sum for charitable giving in Jewish practice. Other named techniques vary the arithmetic: mispar gadol keeps the extended sofit values for every calculation; mispar katan drops the tens and hundreds and reduces every letter to its ones digit; and notarikon and temurah work by acronym and letter substitution rather than summation, treating the alphabet as raw material for wordplay as much as for arithmetic.