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### Grouping Symbols

```
Date: 08/27/98 at 18:00:50
From: Ashley Allen
Subject: Grouping symbols

I need the name of four grouping symbols. I  already know of
parentheses and brackets so that takes care of two. I also need to
know what the missing two symbols look like, if that is possible.
```

```
Date: 08/28/98 at 09:14:59
From: Doctor Peterson
Subject: Re: Grouping symbols

Hi, Ashley. There are three main grouping symbols, and one other that's
used in just a few special cases these days, plus a few other things
that are occasionally used to group parts of an expression.

The three main ones are parentheses (), brackets [], and braces {}.
The other one is the vinculum, a line over an expression, which was
used often in the Middle Ages but now is found in just two places I can
think of: as part of a square root, grouping together the expression
you take the square root of:
_____
\/12+4

and in repeating decimals:
______
1/7 = 0.142857

Some people also consider the fraction bar to be a vinculum, which is
how it originated, since it also groups the numerator and denominator
together without needing parentheses around them:

3+45
------
21+2

Another symbol that occasionally has a grouping function as part of
its job is the absolute value bars:

|5-16|

Each of these symbols also has other more specific uses in some
contexts. Parentheses are used for functions, brackets are used to
mean "largest integer less than" and to surround matrices, braces are
used for sets, and bars are used for determinants.

I hope that's more than you wanted to know, and that the vinculum is
the fourth symbol you were supposed to find. If you find a better one,
let me know!

- Doctor Peterson, The Math Forum
Check out our web site! http://mathforum.org/dr.math/
```

```
TimeStamp: 09/24/98 at 18:55:26
From: The Allen Family
Subject: Thanks

Doctor Peterson,

Thank you very much for answering my question about grouping symbols.
```
Associated Topics:
High School Definitions
Middle School Definitions

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