The so-called ‘Leiden Manuscript’, the collection of Turkic and Mongolic glossaries titled Kitāb Majmūʿ Turjumān Turkī wa-ʿAjamī wa-Muğalī wa-Fārsī, has a yet undeciphered inscription on f. 75b. In this article, the author identifies the script of the inscription as a type of Coptic cursive numerals called ḥurūf al-zimām, which was primarily in use in Egypt for accounting purposes. The consecutive numbers and multiples of 10 and 100 in the inscription may indicate that they were written for practicing numerical letters by someone who had nothing to do with the creation or the copying of the manuscript. The use of zimām numerals in the inscription indicates that the manuscript may have existed in Egypt, and this strengthens the theory advanced by M.Th. Houtsma that the manuscript was created there. Yemen is another possible place of origin of the manuscript due to the close relationship of the Rasūlid dynasty with the Mamlūk sultanate and the fact that some documents with zimām numerals have been found there.