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### Arithmetic Operators

The `awk` language uses the common arithmetic operators when evaluating expressions. All of these arithmetic operators follow normal precedence rules and work as you would expect them to.

The following example uses a file named `grades`, which contains a list of student names as well as three test scores per student (it's a small class):

```Pat   100 97 58
Sandy  84 72 93
Chris  72 92 89
```

This programs takes the file `grades` and prints the average of the scores:

```\$ awk '{ sum = \$2 + \$3 + \$4 ; avg = sum / 3
>        print \$1, avg }' grades
-| Pat 85
-| Sandy 83
-| Chris 84.3333
```

The following list provides the arithmetic operators in `awk`, in order from the highest precedence to the lowest:

`- x`
Negation.
`+ x`
Unary plus; the expression is converted to a number.
`x ^ y`
`x ** y`
Exponentiation; x raised to the y power. `2 ^ 3` has the value eight; the character sequence `**` is equivalent to `^`.
`x * y`
Multiplication.
`x / y`
Division; because all numbers in `awk` are floating-point numbers, the result is not rounded to an integer--`3 / 4` has the value 0.75. (It is a common mistake, especially for C programmers, to forget that all numbers in `awk` are floating-point, and that division of integer-looking constants produces a real number, not an integer.)
`x % y`
Remainder; further discussion is provided in the text, just after this list.
`x + y`
`x - y`
Subtraction.

Unary plus and minus have the same precedence, the multiplication operators all have the same precedence, and addition and subtraction have the same precedence.

When computing the remainder of `x % y`, the quotient is rounded toward zero to an integer and multiplied by y. This result is subtracted from x; this operation is sometimes known as "trunc-mod." The following relation always holds:

```b * int(a / b) + (a % b) == a
```

One possibly undesirable effect of this definition of remainder is that `x % y` is negative if x is negative. Thus:

```-17 % 8 = -1
```

In other `awk` implementations, the signedness of the remainder may be machine-dependent.

Note: The POSIX standard only specifies the use of `^` for exponentiation. For maximum portability, do not use the `**` operator.