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.
Johannes de Sacrobosco
Sacrobosco's "Algorismus" aka "De Arte Numerandi" is thought to have been his first work, and the date is estimated at about 1225, and before 1230. The Hindu–Arabic methods of numerical calculation had arrived in Latin Europe during the previous fifty years but had not been disseminated on a wide scale. Sacrobosco's "Algorismus" was the first text to introduce Hindu–Arabic numerals and procedures into the European university curriculum.