How can the code be modified to ensure that the variable values are properly multiplied in the calculation?

The issue arises from using the concatenation operator (.) instead of the multiplication operator (*) when multiplying the variable values in the calculation. To solve this issue, simply replace the concatenation operator with the multiplication operator in the calculation.

// Incorrect calculation using concatenation operator
$result = $num1 . $num2;

// Correct calculation using multiplication operator
$result = $num1 * $num2;