Bahā’ al-Dīn Muḥammad ibn Ḥusayn al-‘Āmilī, also known as Sheiykh Bahā’ī, was a famous polymath and intellectual luminary of Safavid Persia. He was born in 1547 (953 AH) near the Jabal ‘Āmila in Syria. He migrated with his family to Persia (perhaps to escape the persecution of Shi'a Muslims at the hand of the Ottomans), where he eventually obtained an honored place at the court of Shāh ‘Abbās. He died in Isfahan in 1621 (1030 AH). A prolific author of works on astronomy, mathematics, fiqh (Islamic jurisprudence), and other subjects, al-‘Āmilī was also a poet who wrote in both Persian and Arabic. His most popular literary work, Kashkul (Mendicant's bowl), includes accounts of his many travels in Persia and the Ottoman realms. The majority of al-‘Āmilī's considerable scientific and mathematical output remains to be studied. The al-Khulasa fil hisab (The essentials of arithmetic) was an extremely popular work throughout the Middle East up to the 19th century. It has an introduction and ten chapters, with the tenth chapter including exercises and a conclusion, and is dedicated to Bahādur Khān, a member of the Safavid house. The colophon of the present manuscript indicates that it was copied near Saharanpur, in Mughal India. The manuscript is in Nasta’aliq script written in black and red ink, with geometric shapes in the margins between lines. The copyist states, in Persian, that it was completed on a Friday after the "first part" of the morning. In a couplet he also asks the Lord to forgive the "author, reader, and viewer." A translation of al-Khulasa fil hisab by the German linguist and ethnographer G.H.F. Nesselmann was published in Berlin in 1843. A French edition (based on the German) appeared in 1864.