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# Arithmetic Operators

The arithmetic operators perform mathematical operations on numeric operands. If you use non-numeric operands with the arithmetic operators, ActionScript will attempt to convert the foreign data to a number. For example, `false - true` evaluates to -1 because `false` converts to the numeric value and `true` converts to 1. Similarly, the expression `"3" * "5"` results in the number 15, because the strings “3” and “5” are converted to the numbers 3 and 5 before the multiplication is performed. The `+` operator, however, presents a special case: when used with at least one string operand, it performs a string concatenation operation, not mathematical addition.

If an attempt to convert a non-numeric operand to a number fails, the operand will be set to the special numeric value `NaN`. This results in the entire operation yielding `NaN`. Refer to Table 3.1 for details on numeric conversion.

The addition operator returns the sum of its two operands:

`                  `operand1` + `operand2``

In order to return a meaningful mathematical result, the operands of `+` should be expressions that yield a numeric value, such as:

```234 + 5          // Returns 239
(2 * 3 * 4) + 5  // Returns 29```

The addition operator is unique among the arithmetic operators in that if one or both of its operands are strings, it performs as a string concatenation. Refer to Section 4.6.1 in Chapter 4.

## Increment

A handy variation on addition, the increment operator accepts a single operand and simply adds 1 to its current value. Increment ...

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