Multiply two arbitrary precision numbers

# bcmul

(PHP 4, PHP 5, PHP 7, PHP 8)

bcmul — Multiply two arbitrary precision numbers

### Description

bcmul(string `$num1`, string `$num2`, ?int `$scale` = `null`): string

Multiply `num1` by `num2`.

### Parameters

`num1`

  The left operand, as a string.

`num2`

  The right operand, as a string.

`scale`
  This parameter is used to set the number of digits after the decimal place in the result. If `null`, it will default to the default scale set with bcscale(), or fallback to the value of the `bcmath.scale` INI directive.

### Return Values

Returns the result as a string.

### Errors/Exceptions

This function throws a ValueError in the following cases:

- `num1` or `num2` is not a well-formed BCMath numeric string.
- `scale` is outside the valid range.

### Changelog

Version | Description
--- | ---
8.0.0 | `scale` is now nullable.
7.3.0 | bcmul() now returns numbers with the requested scale. Formerly, the returned numbers may have omitted trailing decimal zeroes.

### Examples

Example #1 bcmul() example

`<?php
echo bcmul('1.34747474747', '35', 3); // 47.161
echo bcmul('2', '4'); // 8
?>`

### Notes

> Note:

> Prior to PHP 7.3.0, bcmul() may return a result with fewer digits after the decimal point than the `scale` parameter would indicate. This only occurs when the result doesn't require all of the precision allowed by the `scale`. For example:

> Example #2 bcmul() scale example

> `<?php
> echo bcmul('5', '2', 2); // prints "10", not "10.00"
> ?>`

### See Also

- bcdiv() - Divide two arbitrary precision numbers
- BcMath\Number::mul() - Multiplies an arbitrary precision number

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