Al-Khawarizmi's work in the field of science is very much, especially in the field of mathematics. His contribution has a major impact on linguistic terms in mathematics, such as algebraic words and algorithms. Algebra is taken from the word in one of his books, then the word algorithm is taken from the word algorithmism, which is the latinization of his name.
Al-Khwarizmi's work is very important, because it is the first notation to use Arabic numerical bases from 1 to 9, 0 and placement value patterns, how to write decimal numbers and the use of root marks, introduce negative signs in the Arab nation, he also explained regarding the four basic operations of calculation, namely; addition, subtraction, multiplication and division.
His works include:
Al-Kitāb al-mukhtaṣar fī ḥisāb al-jabr wa-l-muqābala, this is his most phenomenal work. This is the first book that discusses the systemic solution of linear and quadratic notation. This book made him a famous person, both in the West and East. This work became the basis of algebraic studies in the Renaissance era, and became a major reference in a number of works by great mathematicians such as Leonardo Fibonacci, Gerard of Cremona, Robert of Chaster and Roger Bacon.
Kitāb al-Jam’a wa-l-tafrīq bi-ḥisāb al-Hind is his work in the field of arithmetic. The original book in Arabic was not found, but the translated version in Latin still exists. The translation was carried out in the 12th century by the Adelard of Bath.
His other works are Kitāb ṣūrat al-Arḍ which discusses geography, this work is a geographical deepening of Ptolemy and Claudius, which was later perfected by him. Zīj al-sindhind who discusses astronomy. Risāla fi istikhrāj taʾrīkh al-yahūd which discusses calendars and intercalation cycles. He also wrote about astrolabes and sundials. He still has many other works, but some of them have been lost in time.