The numeral system came to be known to both the Persian mathematician Al-Khwarizmi, whose book On the Calculation with Hindu Numerals written about 825 in Arabic, and the Arab mathematician Al-Kindi, who wrote four volumes, “On the Use of the Indian Numerals” (Ketab fi Isti’mal al-‘Adad al-Hindi) about 830. Their work was principally responsible for the diffusion of the Indian system of numeration in the Middle East and the West.
In the 10th century, Middle-Eastern mathematicians extended the decimal numeral system to include fractions, as recorded in a treatise by Syrianmathematician Abu’l-Hasan al-Uqlidisi in 952–953. The decimal point notation was introduced by Sind ibn Ali, he also wrote the earliest treatise on Arabic numerals.
A distinctive West Arabic variant of the symbols begins to emerge around the 10th century in the Maghreb and Al-Andalus, called ghubar (“sand-table” or “dust-table”) numerals, which are the direct ancestor of the modern Western Arabic numerals used throughout the world.
Some folk etymologies argue that the original forms of these symbols indicated their value through the number of angles they contained, however there is no proof of any such origin.
source: Arabic numerals - Wikipedia
