6

In English, when we want to express parts of wholes and certain numbers of said parts, we use fractions consisting of a denominator indicating how many equal pieces an item has been broken or divided expressed in the ordinal fashion (except for 2 pieces=halves) sitting under a bar or behind a slash under or behind a numerator indicating how many of those pieces are present expressed cardinally prior to the denominator:

1/2 - one-half; 3/4 - three-fourths, and so on...

How did they express this concept and these types of numbers in Latin?

  • Who are "they"? I am not aware of any mathematical texts written in classical Latin. Would, say, 18th and 19th century texts do? – Joonas Ilmavirta May 9 at 2:46
  • When it comes to actually doing mathematics, I can't recall when I've last heard anyone say "three fourths". Usually people would say "three over four" or "three by four" or even "three divided by four". This is just to say that the practices in mathematics and in everyday speech may differ quite a bit. – Joonas Ilmavirta May 9 at 2:47
  • @Joonas Ilmavirta: I simply meant anyone anywhere at anytime, especially in the past, who spoke Latin fluently, like Romans, etc. Also I did read the first one, but it said nothing about fractions, division problems, yes, but not fractions as I know them as a means to express values between 0 and 1. – Media Matella Lucretia Flores May 9 at 5:10
  • In other words, I don't care about time or place, just as long as it is commonly accepted, so both an ancient and a modern approach would be welcomed and highly appreciated here. – Media Matella Lucretia Flores May 9 at 5:25
4

Fractions were written, as you might expect, using Roman numerals. This wasn't particularly elegant for anything more complex than adding and subtracting, but it worked great for commerce, and that was where it was most often used.

The units worked sort of like this:

  • I = 1 (as) [vertical line]
  • S = 1/2 (semis) [letter S]
  • 𐆑 (or •) = 1/12 (uncia = ounce) [horizontal line or dot]
  • 𐆐 (or ••) = 2/12 (sextans) [two horizontal lines or dots]
    • And so on for multiples of 1/12
  • 𐆒 = 1/24 (semuncia = half an ounce) [either capital sigma, or British pound sign without the crossbar]
  • Ɔ = 1/48 (sicilius) [backward C]
  • 𐆓 = 1/72 (sextula = 1/6 ounce) [backward S]
  • 𐆔 = 1/144 (half a sextula) [backward S with a line through it]
  • ℈ = 1/288 (scripulum = scruple) [backward C with a line through it]
  • 𐆕 = 1/1728 (siliqua) [double backward C]

Two things to notice here!

One, the fraction system works sort of in base-12, because it turns out it's a lot easier to divide things when you're in base-12.

And two, most of these names are units of currency, which isn't a coincidence. Many coins were equivalent to weights (since their value came from their weight in precious metal), and were given names either from their value (sextans = "one-sixth") or from how much they weighed (siliqua = "carob seed"). Since these names meant fractions of currency, or fractions of weight, they got applied to fractions of other things too.

Here's an engineering example, from Frontinus's De Aquibus ("About Aqueducts"), with two translations (both mine). This is in the middle of a list of specifications of pipes:

Fistula quadragenaria: diametri digitos septem 𐆑𐆒℈III, perimetri digitos XXII𐆐𐆐𐆑, capit quinarias XXXIIS𐆑.

The forty-pipe: diameter seven digits, plus one ounce, plus a half-ounce, plus three scruples. Circumference 22 digits, plus five ounces. It holds 32 quinariae, plus a half, plus an ounce.

Pipe #40. Diameter: 7 + 1/12 + 1/24 + 3/288. Circumference: 22 + 5/12. Cross-sectional area: 32 + 1/2 + 1/12.

Frontinus uses a shorthand here: a full number after a fractional unit means "multiply that unit by this number". So ℈III means "three scruples". I've never seen this used with ounces, only smaller amounts.

So to answer your examples:

  • "One-half" is S
  • "Three-fourths" is S•••

I'm not entirely sure how these numbers would have been spoken out loud, since the main sources we have are written, and numerals were pretty much always used in writing (like how in English we'd write "69105.1" instead of "sixty-nine thousand, one hundred and five, and one-tenth"). But based on the currency, here's my best guess, using the example from Frontinus again:

septem 𐆑𐆒℈III

Septem, et uncia, et semuncia, et scripuli tres

In other words, join the units together with et, using normal numbers for multipliers.

Google also leads me to this table on Wikipedia, which gives special names for each integer multiple of one-twelfth.

EDIT: This is how the list of symbols looks for me, using Google Noto fonts. Unfortunately I can't find a way to align it with the actual list, and turning the text of the answer into an image makes it useless for screen readers. picture of badly supported Unicode characters

  • 3
    I don't know if it is you or I, but my screen can only make out four of those symbols (the rest show as hollow squares). – Media Matella Lucretia Flores May 9 at 5:14
  • Also, by pronounce I mean write in words, spelling them out, so that they can be read in that language (I know how to pronounce Classical Latin). That said can you please rewrite that quote transliterating those numbers to spelled out words, so I can pronounce them? – Media Matella Lucretia Flores May 9 at 5:21
  • @MediaMatellaLucretiaFlores Added descriptions of the symbols; unfortunately Unicode support is not as good as it should be still. Also added my best guess as to how it would be written out in words, but a guess is all I have I'm afraid. – Draconis May 9 at 16:13
  • 1
    Is there a picture you can post that has a table or something with the illegible marks showing? – Media Matella Lucretia Flores May 10 at 0:28
  • @MediaMatellaLucretiaFlores How's that? – Draconis May 10 at 17:56
1

Quadrans, a quarter.

To answer your questions precisely, (but notice that with egit, ='there is lacking,' Varro's definition shows another formula to use) the word for three-quarters is

dōdrans, = threequarters, or more precisely nine twelfths.
[ita dict. quod ad deficiendum assem desit quadrans. Varr.]
dodrantalis, adj, three-quarter.

'Half' is more complicated:

Dimidium, pars media; medietas.

but in many cases there is a specific word.

semiiugerum, half an acre;
semipes, half a foot;
sesquipes, a foot and a half.

Notice that dōdrans fits the twelfths mentioned by Draconis in his post. [Also, I'm sure I read somewhere that 'five sixths,' was quinque partes; 'seven-eighths,' septem partes; but I can only find any support at all for 'nine tenths,' novem vero partes. ]

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