Quick:  multiply DVII by XVIII.  Before you could work the problem you translated it into Arabic numbers didn’t you?

The person you can thank, or blame, for your ability to multiply and divide is the mathematician and astronomer Muhammad ibn Musa al-Khwarizmi (ca. 783-847), whose name lives on in a mangled form as “algorithm.  (Honest.  Take a moment to sound it out.)

We know very little about al-Kwarizmi’s life.  His name suggests he was born in the region of Khwarazm in what is now Uzbekistan.  There are suggestions that he was a Zoroastrian, who may have converted to Islam.

We know a lot about al-Kwarizmi’s work as a scholar in al-Mansur’s court in Baghdad.  He introduced what were then called “Hindu numerals” to the Muslim world.  He produced an important astronomical chart (zij) that made it possible to calculate the positions of the sun, the moon and the major planets and to tell time based on stellar and solar observations.

Al-Kwarizmi’s most important contribution to science was a ground-breaking mathematical treatise: al-Kitab al-Mukhtasar fi Hisab al-Jebr wal-Muqabala. The title translates to The Compendium on Calculation by Restoration and Balancing, but the book is most often referred to as al-jebr, or algebra.  His treatise was a combination of mathematical theory and practical examples related to inheritances, property division, land measurements, and canal digging.  He was the inventor both of quadratic equations and the dreaded word problem.    (Some of his word problems became classics, which meant they were still giving schoolboys grief several centuries later.)

So, the next time you need to calculate how long it will take for two cars to meet in Dubuque if one car leaves Minneapolis going 60 miles an hour and the other leaves Peoria traveling 75 miles an hour?  Thank al-Khwarizmi.

This post previously appeared in Wonders & Marvels.