What is a Parenthesis?

Date: 07/17/2000 at 20:34:33
From: Shatara Nivens
Subject: Parenthesis

I was wondering if you could help me figure out what the mathematical 
term "parenthesis" means. 

Thanks.

Date: 07/17/2000 at 20:48:48
From: Doctor Peterson
Subject: Re: Parenthesis

Hi, Shatara.

This is a left parenthesis:  (

This is a right parenthesis: )

The plural is "parentheses": ()

Mathematically, they are used to mark an expression that is to be 
treated as a single number in a larger expression; for example, to 
evaluate the expression:

     2 * (3 + 4)

you first evaluate (find the value of) the expression 3 * 4, then 
replace the "parenthetical expression" with its value:

     2 * 7 = 14

To learn more about how they are used, see our Order of Operations 
FAQ:

   http://mathforum.org/dr.math/faq/faq.order.operations.html   

If you're interested, the word "parenthesis" comes from a Greek word 
that means "insertion"; the word is used in grammar for both of the 
symbols themselves, and for an entire phrase that has been inserted 
into a sentence (like the parenthesis at the end of this sentence). 
But in math, we use it only to refer to the symbols themselves, as far 
as I know.

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