What are the advantages and disadvantages of using include() to incorporate PHP scripts for calculations in a separate file?

When incorporating PHP scripts for calculations in a separate file using include(), the advantages include better organization of code, reusability of functions across multiple files, and easier maintenance. However, some disadvantages may include potential security risks if the included file is not properly sanitized, and performance overhead due to file inclusion.

// main.php

include('calculations.php');

$result = add(5, 3);
echo $result;

// calculations.php

function add($num1, $num2) {
    return $num1 + $num2;
}