ا ب ت ث ج ح خ د ذ ر ز س ش ص ض ط ظ ع غ ف ق ك ل م ن ه و ي
The Abjad numerals are a decimal numeral system 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 8th century Arabic numerals. In modern Arabic, the word abjadīyah means 'alphabet' in general.
In the Abjad system, the first letter of the Arabic alphabet, alif, is used to represent 1; the second letter, bāʼ, is used to represent 2, etc. Individual letters also represent 10s and 100s: yāʼ for 10, kāf for 20, qāf for 100, etc.
The word abjad (أبجد) itself derives from the first four letters (A-B-G-D) in the Phoenician alphabet, Aramaic alphabet, Hebrew 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: thāʼ=500, etc.