Naming Numbers

Date: 09/26/2002 at 10:15:59
From: Susan Guest
Subject: Naming numbers

I am a fifth-grade math teacher. I have a student who insists that 
2400 (twenty-four hundred) is not a number. It can only be named as 
2,400 (two thousand four hundred). I know that it is not a COUNTING 
number, but it is naming a quantity and should be considered a number.
This student is becoming somewhat obnoxious about this. HELP! Who's 
right?

Date: 09/26/2002 at 10:46:39
From: Doctor Ian
Subject: Re: Naming numbers

Hi Susan,

By the same logic, 'four hundred' wouldn't be a number either, would 
it?  After all, when you say 'four hundred', you're implying that 
you're multiplying one hundred by four.  

Any number can be called by a variety of names. For example, here are 
just a few names for 2400:

  two thousand four hundred

  twenty-four hundred

  two point four times ten to the third power

  two hundred dozen

  one hundred twenty score

  sixteen and three-fourths gross

I'll close with this excerpt from the _Chicago Manual of Style_ (14th 
ed.), Section 8.2, 'General Principles':

  If a number between one thousand and ten thousand 
  can be expressed in terms of hundreds, that style is
  preferred to numerals:

     In response to the question, he wrote an essay
     of fifteen hundred words.

So I think it's pretty clear which of you is right. 

Does this help? 

- Doctor Ian, The Math Forum
  http://mathforum.org/dr.math/