Algebra was invented by the Muslim mathematician Al-Khwarizmiin the book he wrote in 820. Algebra is the Arabic word (aljabr) for "equation", and the word "algorithm" comes from the author's name, Al-Khwarizmi. He is rightly known as "the father of Algebra".

-J. J. O'Conner and E. F. Robertson wrote in the MacTutor History of Mathematics archive

Al-Battani (850-922) was a Muslim astronomer who accurately determined the length of the solar year as being 365 days, 5 hours, 46 minutes and 24 seconds.

Reference:-

*http://en.wikipedia.org/wiki/Mu%E1%B8%A5ammad_ibn_J%C4%81bir_al-%E1%B8%A4arr%C4%81n%C4%AB_al-Batt%C4%81n%C4%AB

*http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Battani.html

*MacTutor History of Mathematics archive, University of St Andrews.