Numerical digit
From India, the thriving trade between Islamic sultans and Africa carried the concept to Cairo. Arabic mathematicians extended the system to include decimal fractions, and Muḥammad ibn Mūsā al-Ḵwārizmī wrote an important work about it in the 9th  century. The modern Arabic numerals were introduced to Europe with the translation of this work in the 12th century in Spain and Leonardo of Pisa's "Liber Abaci" of 1201. In Europe, the complete Indian system with the zero was derived from the Arabs in the 12th century.
History of the Hindu–Arabic numeral system
Historians trace modern numerals in most languages to the Brahmi numerals, which were in use around the middle of the 3rd century BC. The place value system, however, developed later. The Brahmi numerals have been found in inscriptions in caves and on coins in regions near Pune, and Uttar Pradesh. These numerals (with slight variations) were in use up to the 4th century.