## Medieval Mathematics

currently playing on my iPod: Modern Man by Arcade Fire

While reading through the latest draft of my manuscript, I came across the word “numbers”. So what? Well, there is a problem. Maybe not so much in just the simple use of the word “number” but in the connotation of the word. Common medieval folk in England did not use numbers as we do today. The Arabic-Hindu numbers with which we are familiar were unheard of.  The concept of zero, when it was introduced, was seen by many as sorcery. When medieval folks wished to do business, they used other techniques. Three of which I’ll mention today.

One was the abacus. You probably know what it is–a little contraption with beads to slide and so forth. There were actually professionals who did nothing but hire their abacus services out to varying types of businessmen. They were big on keeping the new Arabic-Hindu numerals out of England.

Another technique used to count and do what we think of as adding and subtracting was finger counting. Yes, you heard me right. Using the old fingers. Just like your 3rd grade teacher’s worst nightmare. But this finger counting was anything but simple. It involved lowering the pinkie for one, and then continued through such challenging contortions as raising some fingers, lowering others, and making a circle out of the thumb and index finger. The ring finger was lowered to represent “six”–a perfect, sacred number–because it was known to house a vein that ran directly to the heart. Just as everything else in medieval England, all things had meaning, magic, and religion tied into them. All in all, a very interesting system.

You’ve heard of tally marks, right? I know from my elementary school teacher days that we still teach tally mark math to our kids here in the US. Tally marks are simple lines used to indicate amounts. In medieval Europe, people used tally sticks. A piece of hazel wood would be carved in varying widths to indicate varying amounts of money. The wider the slice, the higher the amount. The piece of wood–the tally stick–was then split and shared between businessmen and their customers. Tally sticks served as a record of the business. This widespread use of tally sticks also led to tally mark calendars used by clergy to figure the date of Easter and other such movable feasts.

I’ve only scratched the surface (no tally stick pun intended) of medieval mathematics. The actual process of adding, subtracting, dividing, and so forth was wholly different than modern procedures. But I will leave such musings to the math wizards who used to tutor me in 10th grade geometry. Back to writing fun fiction…

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