How to read the fraction 4/21?

emma.learns

Senior Member
Chinese - China
Dear all,

How should I read 4/21 when the denominator is 21?

Is it four twenty-first or four twenty-firsts?

I know we can say four over twenty-one but I'd also like to know some other ways to read the fraction.

Thank you!
 
  • heypresto

    Senior Member
    English - England
    Either 'a fifth' or 'one fifth'.

    Or 'four twentieths'. But this is unlikely, as it's unlikely anyone would write the fraction '4/20', without further reducing it to '1/5'.
     

    natkretep

    Moderato con anima (English Only)
    English (Singapore/UK), basic Chinese
    If you're reading it as a fraction, you need to use the ordinal for the denominator: one fifth, two tenths, four twentieths.

    If you're reading it the way it's written, you can use the cardinal: one over five, two over ten, four over twenty.
     

    Lun-14

    Banned
    Hindi
    Either 'a fifth' or 'one fifth'.

    Or 'four twentieths'. But this is unlikely, as it's unlikely anyone would write the fraction '4/20', without further reducing it to '1/5'.
    What would you say about my four suggestions in #5 - are they correct?
     

    Retired-teacher

    Senior Member
    British English
    The fact that 4/20 = 1/5 is not really relevant. There may be a problem where changing 1/5 into 4/20 is useful. I would call this four twentieths.

    4/21 is not so easy. "Four twenty firsts" sounds wrong, so I think I would say "four twenty oneths" even though that sounds ridiculous.
     

    kentix

    Senior Member
    English - U.S.
    In your comment #5 you misunderstood what he wrote.

    A/one fifth.

    He meant you could use A or you could use one in front of fifth. Your choice. You read it all together as one thing.
     

    kentix

    Senior Member
    English - U.S.
    Four twenty firsts" sounds wrong, so I think I would say "four twenty oneths" even though that sounds ridiculous.
    In the U.S. we would definitely say four twenty-firsts.

    We would definitely not say 4 by 21. Those would be the dimensions of a rectangle.
     

    Barque

    Senior Member
    Tamil
    If you're reading it the way it's written, you can use the cardinal: one over five, two over ten, four over twenty.
    The usual Indian English way of saying it is with "by" instead of "over", which explains Semeeran's question. (By is short for divided by.)
     

    Packard

    Senior Member
    USA, English
    I see. Thanks.
    Do you also read "4/21" as "four over twenty-one" in BE?
    If it were a common fraction we (USA) would say:

    • Three sixteenths
    • Five thirty-seconds
    • nine sixty-fourths
    • etc.

    But for 4/21 it would be awkward to say "four twenty-firsts" (better than "four twenty-oneths.") :)

    If I were pressed to use the fraction then I would also say "four over twenty-one", though in a sentence it really does not work.


    What is the size of the screw you are using?

    It's a four over twenty-one.


    The above sounds really weird to me, versus below which sounds fine:


    What is the size of the screw you are using?

    It's a three sixteenths.
     

    Andygc

    Senior Member
    British English
    Do you also read "4/21" as "four over twenty-one" in BE?
    That's possible. But it is a very unusual fraction. I cannot ever remember dividing anything into twenty-firsts. I have rules that measure twentieths, twenty-fourths and thirty-seconds of an inch, but I've never seen one that can measure twenty-firsts.
     

    Glenfarclas

    Senior Member
    English (American)
    That's possible. But it is a very unusual fraction. I cannot ever remember dividing anything into twenty-firsts. I have rules that measure twentieths, twenty-fourths and thirty-seconds of an inch, but I've never seen one that can measure twenty-firsts.
    It presumably wouldn't arise from a measurement system, but rather from some formula like a²/(b*c), in a particular situation where a=2, b=7, and c=3.

    And I can't really imagine saying it any way other than "four over twenty-one."
     

    Packard

    Senior Member
    USA, English
    It presumably wouldn't arise from a measurement system, but rather from some formula like a²/(b*c), in a particular situation where a=2, b=7, and c=3.

    And I can't really imagine saying it any way other than "four over twenty-one."
    It is a meaningless measurement. You have the "4/21". What do you do with it? You cannot measure it or transfer it to another surface or product. So if you don't convert it to decimal equivalent (inches or metric) it is just a number and not a usable measurement.

    What size do you need me to cut this plywood to?

    14 inches and 4/21".

    And how do I measure that?

    What? You don't have a 21th measuring tape? What kind of carpenter are you?
     

    kentix

    Senior Member
    English - U.S.
    In pure math you run into fractions of all kinds. You have to pronounce them whether they are used to measure anything or not.

    4/932 = four nine-hundred and thirty-seconds

    And I can't really imagine saying it any way other than "four over twenty-one."
    And I speak American English also and can't ever imagine saying it that way. Do you have a math background?
     
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    kentix

    Senior Member
    English - U.S.
    I wasn't a math major but took a lot of high level college math (very near Chicago) and can't recall ever hearing people using that form. Granted, you don't talk about a lot of specific fractions in college level math.

    How would you say this problem out loud?

    5/6 + 4/21 =
     
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