# Commentary on the Gift of Arithmetic

## Description

This work is by Abd-Allāh Ibn Bahā al-Din Muhammad Ibn Abd-Allāh al-Shanshāri al-Shāfīī, an expert in calculating al-Fardī (inheritance portions). The cover page of the manuscript bears a magical form or talisman for finding a lost object. The main text is a detailed commentary on Tuhfat al-ahbāb fi al-hisāb (The friendly gift of arithmetic) by the renowned Egyptian scholar Badr al-Dīn Muhammad Ibn Muhammad Ibn Ahmad (1423–1506), known as the Sibt (grandson of) al-Mardini, who taught arithmetic and astronomy in Alazhar for several years. The original work has an introduction and is divided into three sections. The commentary meticulously goes through the stylistic as well as the technical contents of Sibt al-Mardini’s work, focusing on the science of the division of inheritance (ilm al-farā'id) and arithmetic. The introduction discusses the subject matter of arithmetic, including numbers and counting (enumeration), and offers a definition of numbers. Each number is said to be made of units; alternatively, each number can be defined as half of the two numbers that are immediately before and after it. The author then goes through classes of numbers, such as square roots and cube roots, and discusses basic operations on numbers. The manuscript is divided into two parts. On the first folio of the second part, a procedure is described, in the form of an arithmetic problem, for determining whether a sick person is likely to live or die. At the end of the manuscript, a short, half-page versified work appears describing the procedure or algorithm for solving equations, but this second part of the manuscript seems incomplete and truncated. This manuscript, like several others in the series, once belonged in the library of Hajj Ibrāhīm Sar-Askar in Cairo.

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