The Two Abjad Orders

Hisab al-jummal, the reckoning of the total, assigns each of the twenty eight letters of the Arabic alphabet a fixed numeric value and sums a word's letters to find its total, the same basic operation Hebrew gematria and Greek isopsephy perform on their own alphabets. Two distinct orderings of the values survive and remain in use in different regions. The standard Eastern or Mashriqi order follows the historic sequence of the Northwest Semitic abjad that Hebrew, Aramaic and Arabic all ultimately share, running alif through ghayn in a pattern that mirrors the old Phoenician letter order rather than the alphabetical order taught for reading and writing today.

A separate Western or Maghribi order, historically used in North Africa and in Islamic Spain, rearranges several of the later letters differently, so the same word can sum to two different totals depending on which regional convention is applied, a genuine and documented variation rather than an error in either system. Because the abjad numerals also served as an alternative to Hindu-Arabic numerals for ordinary counting and dating for centuries, mastering the value table was practical knowledge for scribes and astronomers as much as it was an esoteric skill.