In 77 1 A.D., an Indian traveler, Maoka, made a long journey to Baghdad, the capital of Abbasid Dynasty of Arab Empire. Maoka dedicated an Indian astronomical work "Sidanta" that he carried with him to the then caliph (king) Mansour. Mansour cherished the book very much and ordered the translator to translate it into Arabic. Translated into Sindh Sindh Sindh. This book uses a lot of Indian figures. As a result, Indian numbers were absorbed and adopted by Arabs.
Since then, Arabs have gradually given up the original 28 letters as a symbol of calculation, and widely used Indian numerals, and in practice, they have also modified and improved Indian numerals to make them easier to write.
When Arabs got hold of Indian figures, they soon introduced them to Europeans. It was very inconvenient for Europeans in the Middle Ages to use long Roman numerals when counting. Therefore, as soon as the simple and clear Indian figures spread to Europe, they were welcomed by Europeans. But in the beginning, Indian numerals replaced Roman numerals, but it was strongly opposed by the Pope because it was knowledge from "pagans". But practice has proved that the Indian figure is far superior to the Roman figure.