Is this how you write these fractions in words?

5/21 is five twenty-ones, 1/21 is one twenty-one. Can someone please clear this for me?

I know 1/4 is one-quarter or one-fourth and 2/5 is two-fifths and 5/25 is five twenty-fifths.

  • 5
    "5/21" is "five twentyfirsts".
    – Hot Licks
    Aug 20, 2015 at 12:45
  • I'm struggling with this also, what about one twenty oneth May 18, 2019 at 8:39
  • @LovehateEnglish - No. That's not a viable option. Deadrat's answer is the correct one here. Also see my comment on Sydney's answer.
    – Jim
    May 18, 2019 at 10:52
  • @Jim It most certainly is a viable option. Some dictionaries list it as nonstandard, but I reckon it to be more common than twenty-first in this particular usage, at least where I live. Because of it's more general usage as an abstract number idea, as in minus oneth, hundred oneth, etc. I'd use it for numbers as numbers. But I use the ordinal first as well, mostly when numbers are counting things or dividing stuff. As a commenter to the same question on Reddit remarked - it is really a short form of one twenty-first part.
    – Phil Sweet
    May 18, 2019 at 16:42
  • @PhilSweet - nonstandard = not viable in my book. (Outside of the non-standard environment). I might say "one twenty oneth" to my friends if I was trying to make them laugh, but never when I was being serious.
    – Jim
    May 18, 2019 at 17:12

3 Answers 3


You will find that dictionaries like this one use the ordinal to define the fraction:

being one of 21 equal parts into which something is divisible <a twenty-first share of the money>

The courts in New Jersey have no trouble using the twenty-first part of estates divided per stirpes:

Therefore, upon the death of Frank, one-seventh equals three-twenty-firsts passed to his son. Anna, dying childless, her two-sevenths equals six-twenty-firsts passed to Mary , Henry, and William equally; two-twenty-firsts to each.


I would say "one over twenty-one," or "one divided by twenty-one." For more information look at this website.

Edit As Jim has pointed out in the comments, "one twenty-first" and "five twenty-firsts" are also correct pronunciations, although they might be a little awkward to say.

  • 1
    I would say five twenty-firsts. one twenty-first.
    – Jim
    Aug 20, 2015 at 4:10
  • @Jim, those answers are also correct but I think that they sound slightly akward. Are you suggesting that my answers are incorrect? If so, why?
    – Sydney
    Aug 20, 2015 at 4:24
  • I'm with Sydney! One over 21. Three over 21. Etc. Aug 20, 2015 at 4:39
  • 1
    If OP had wanted “one over twenty-one”. He would have said, “I know 1/4 is one over four and 2/5 is two over five.” OP is clearly asking for how fractions akin to one fourth and two fifths are pronounced, When you say “five over twenty five” you are copping out and proniuncing the ratio not the fraction. To pronounce the fraction you can think about what position a runner would be in if they came in in the position of the number in the denominstor: fifth, twenty-first, four hundred and thirty second. Then say the numerator and the race position (plural if the numerator is not equal to one.)
    – Jim
    Aug 20, 2015 at 4:56

Wiktionary states that oneth - and, I guess, beyond - is a


(in compounds with twenty-, thirty-, forty-, etc.) A fractional part of an integer ending in one.

(in algebraic expressions) An ordinal value that is represented by an expression ending in 1 such as the (n + 1)th.

In mathematical expressions such as (n + m), where these are variables, for (cardinal) numbers, say, in equations, is there an ordinal expression for m?

As well, what if there are numbers "below" zero, as there may be numbers "above" the reals of infinity, its levels, and, then, the hyperreals, and surreals? I mean, what if zero is a number, ie, the first (integer) number? Then we run into stuff like calling the 1800's the nineteenth century. Perhaps, it's best to put n equal to zero, with m equal to the repeating decimal fraction 0.238095 . Then it, too, is just another number. And, we see what the number is made of.

  • I was about to cancel the downvote, wondering why someone had given it. Then I read the irrelevancies below the blockquote. Sep 27, 2020 at 15:50

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