Writing Numbers with HyphensDate: 06/04/2003 at 16:25:36 From: Brian Subject: Writing numbers with hyphens Why do we hyphenate one hundred-millionth, but we don't hyphenate one hundred million? Date: 06/04/2003 at 19:33:13 From: Doctor Greenie Subject: Re: Writing numbers with hyphens Hi, Brian - I'm not an expert on this, but I know why I think this is the case. When we say "one hundred million," the 'unit' of measure is millions, and we are counting one hundred of them. When we say one hundred-millionth, the 'unit' of measure is neither hundreds nor millionths; it is hundred-millionths, and we are counting one of them. - Doctor Greenie, The Math Forum http://mathforum.org/dr.math/ Date: 06/05/2003 at 11:07:52 From: Doctor Peterson Subject: Re: Writing numbers with hyphens Hi, Brian. Here is another perspective on the same basic idea Dr. Greenie expressed. To make it a little clearer at some points, I will use "two hundred-millionths" as my example. We COULD hyphenate two hundred million as two-hundred million, or as two hundred-million, or even as two-hundred-million, if we wanted to, and it wouldn't change the meaning, which is two times a hundred times a million. We don't do so because it isn't necessary; multiplication is associative. 200,000,000 = 2 * 100 * 1,000,000 two hundred million But the fraction is different: it means not two times a hundred times a millionth, but two times a (hundred millionth); or alternatively, two divided by a (hundred million). Just as in algebra we use parentheses to group the parts that must be kept together, in English we hyphenate them, turning "hundred millionth" into a single word. 2/100,000,000 = 2 / (100 * 1,000,000) two hundred-millionths 200/1,000,000 = (2 * 100) / 1,000,000 two-hundred millionths In the latter case we probably would not hyphenate as I showed, for the same reason we don't have to parenthesize the expression; we assume that numbers are grouped from left to right if not otherwise specified. So we hyphenate the fraction because division is not associative! English is not quite as irrational as it often seems. If you have any further questions, feel free to write back. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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