A treatise on general arithmetic by the celebrated astronomer Ghiyās al-Dīn Jamshīd b. Mas'ūd b. Maḥmūd al-Ṭayyib al-Kāshī, commonly known as Al-Ghayyās, (d. ca. 1436 C.E.) who dedicated the work to Mīrzā Ulugh Beg, grandson of Tīmūr (see fol. 4b). The author, who is reputed to have possessed rough manners, with little or no knowledge of the etiquette of the Court, was nevertheless a favourite with Ulugh Beg, who had appointed him one of the four keepers of his observatory, which had been built in the north-east of Samarqand in 823 A.H. (1420 C.E.).