The word algebra is just one of the legacies given to the world of mathematics by al-Khwarizmi (KWAR-iz-mee), a mathematician in the city of Baghdad (now capital of Iraq) who wrote Kitab al-jabr wa al-muquabalah. The English name for algebra, a branch of mathematics used for determining unknown quantities, is taken from the second word of the book's title.
Al-Khwarizmi was not only interested in mathematics as an abstract study, but for its practical application; thus one of the principal uses for algebra, as described in his book, was for helping men divide up their inheritances proportionately. In assessing business transactions from a mathematical standpoint, al-Khwarizmi maintained that these transactions involved "two ideas," quantity and cost, and "four numbers"— unit of measure, price per unit, the quantity the buyer wants to purchase, and the total cost.
As with Aryabhata, al-Khwarizmi and his readers considered mathematics merely as a tool in service to other things, including astronomy. The latter was particularly important to Muslims, who needed to know the exact location of the holy city of Mecca, toward which they prayed five times a day. He offered tables and techniques for computing the direction to Mecca and the five times for prayer, which were based on the Sun's position.
Al-Khwarizmi's ideas would prove perhaps even more influential in the West than in the Middle East. A testament to his impact is the word algorithm, a term derived from his name and referring to any kind of regularly recurring mathematical operation such as those routinely performed by a computer. One modern scholar maintained that al-Khwarizmi was the single most important mathematician in a fifteen-hundred-year period between about 100 b. c. and the mid-1400s.
World History
