Here’s how the Romans used fractions | Living - Answer Man - Belleville News-Democrat

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Roger Schlueter, BND's Answer Man  - Got questions? You've come to the right place.

Q: Your most recent answer on the Roman calendar reminded me of another question I’ve had for years. With their cumbersome system of using letters for numbers, how did Romans ever write fractions?

K.C., of Millstadt

Photo: Answer Man

A: This answer should have all students who struggle with their math homework wishing for a time machine: According to experts, there’s no evidence that young Romans ever sat around trying to find the lowest common denominator — at least, not as we know it today.

“The Romans didn’t have a standard way to write fractions using their numerals,” “Dr. Math” says at mathforum.com. “Instead, they just wrote out the word for the fraction. For example, two-sevenths was ‘duae septimae’ and three-eighths was ‘tres ocatavae.’”

To do actual calculations, they employed a unit known as the “uncia.” If that sounds familiar, it should. An “uncia” started out as one-twelfth of an “as,” which was a Roman unit of weight. As a result, ”uncia” evolved into our “ounce.”
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Source: Belleville News-Democrat (blog)