Abjad Calculation
Abjad calculation (Abjad numerals) is an ancient calculation system that assigns a numerical value to each letter of the Arabic alphabet. The word "Abjad" is formed from the combination of the first four letters (Alif-Ba-Jim-Dal) in the old arrangement of the Arabic alphabet. This system has been used in Islamic civilization for centuries in a wide range of fields from astronomy to medicine, from literature to Sufism.