Abu’l Hasan Ahmad ibn Ibrahim Al-Uqlidisi;
(Arabic: أبو الحسن أحمد بن ابراهيم الإقليدسي) was a Muslim Arab mathematician, who was active in Damascus and Baghdad. He wrote the earliest surviving book on the positional use of the Arabic numerals, Kitab al-Fusul fi al-Hisab al-Hindi (The Arithemetics of Al-Uqlidisi) around 952. It is especially notable for its treatment of decimal fractions, and that it showed how to carry out calculations without deletions.
While the Persian mathematician Jamshīd al-Kāshī claimed to have discovered decimal fractions himself in the 15th century, J. Lennart Berggren notes that he was mistaken, as decimal fractions were first used five centuries before him by al-Uqlidisi as early as the 10th century.