Abjad numerals
Value Letter Name Trans- literation
10 ي yāʾ y / ī
20 ك kāf k
30 ل lām l
40 م mīm m
50 ن nūn n
60 ص ṣād ṣ
70 ع ʿayn ʿ
80 ف fāʾ f
90 ض ḍād ḍ
The Abjad numerals, also called Hisab al-Jummal (, ), are a decimal alphabetic numeral system/alphanumeric code, in which the 28 letters of the Arabic alphabet are assigned numerical values. They have been used in the Arabic-speaking world since before the eighth century when positional Arabic numerals were adopted. In modern Arabic, the word () means 'alphabet' in general. In the Abjad system, the first letter of the Arabic alphabet, ʾalif, is used to represent 1; the second letter, bāʾ, is used to represent 2, etc. Individual letters also represent 10s and 100s: yāʾ for 10, kāf for 20, qāf for 100, etc. The word ʾabjad () itself derives from the first four letters (A-B-J-D) of the Semitic alphabet, including the Aramaic alphabet, Hebrew alphabet, Phoenician alphabet, and other scripts for Semitic languages. These older alphabets contained only 22 letters, stopping at taw, numerically equivalent to 400. The Arabic Abjad system continues at this point with letters not found in other alphabets: thāʾ= 500, etc. Abjad numerals in Arabic are similar to the earlier alphanumeric codes of Hebrew gematria and Greek isopsephy.