When the letters of the Arabic alphabet are used with a numerical value, similar to “roman numerals” in Latin script, they have the values in the table below. This numbering system is called “abjad“, from the first four letters of the sequence. The letters are usually written connected, so e.g. “124” would be written as “قكد”.
This use of Arabic letters is common in prefaces to printed books, and in the foliation and quire-numbering of Arabic manuscripts.
See: Weil, G.; Colin, G.S.. ” Abd̲j̲ad.” Encyclopaedia of Islam, Second Edition. Brill Online , 2012.
Note: There are regional variations in the abjad system: in the Maghreb, sīn and shīn occupy different positions, and therefore have different numerical values.
See: Blois, F.C. de. ” Sīn and S̲h̲īn.” Encyclopaedia of Islam, Second Edition. Brill Online, 2012.
Conversion of Preliminary page numbers in Classical Arabic to International form.