Opposite of Percentage

Date: 07/31/2001 at 20:45:01
From: Marty Ryerson
Subject: Term for the "opposite" of percentage

Hi,

I am beginning to wonder if there *is* an answer to this.

I am trying to write a document explaining a common procedure, namely, 
calculating a discounted price. To calculate the discount, you 
multiply the "base" by the "percent discount" to yield "percentage."  
At least, these were the terms I was taught.

So, if the price is $32 and the discount is 15%, then you multiply 32 
times .15 to get the amount that is to be subtracted from the initial 
price ($4.80) to yield the discounted price ($27.20). I have been 
taught that the "initial price" ($32) is the "base," the .15 is the 
"percent" or "discount rate," and the resulting discount amount 
($4.80), is the "percentage."

Another way to calculate the final price would be to subtract the 
percentage from 100 (100% - 15% = 85%) and then multiply that result 
by the original price (.85 times $32 = 27.20).  Or, as it appears in 
many computer programs, net = price * (1-discount_rate), where it is 
understood that discount_rate is a decimal fraction.

My question is one of terminology. What is the name given to the term 
"(1-discount_rate)" in this example? I have looked up reciprocal, 
complement, inverse, etc., but none of those fits. I need to be able 
to define this word once and then use it repeatedly in my document, 
rather that explaining it every time I use it, which will be many 
times.

Thanks for any help.

Marty

Date: 07/31/2001 at 22:39:23
From: Doctor Peterson
Subject: Re: Term for the "opposite" of percentage

Hi, Marty.

What you want is "the complement of the discount rate." Here is one 
site I've found that defines it:

   Trade Discounts - Business Mathematics, Confederation College
   http://courses.confederationc.on.ca/bm105/part2/unit7/bm7s1.htm   

   Trade discounts are used in the retail sector. They are used to 
   calculate how much a retailer will pay a manufacturer for a given 
   product...

   Complement of a Trade Discount: This is the difference between the 
   discount rate and 100%. The complement can be any percent that 
   results when you subtract the trade discount rate from 100%.


In general mathematicians use the word "complement" to mean "all 
except ..." or "the whole minus a given part; here it means 1 minus a 
fraction - though I haven't found any dictionary that gives this 
definition.

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