(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_mul — Multiply numbers
   Multiplies num1 by num2
   and returns the result.
  
A GMP object.
Example #1 gmp_mul() example
<?php
$mul = gmp_mul("12345678", "2000");
echo gmp_strval($mul) . "\n";
?>
The above example will output:
24691356000