How can the use of quotation marks for numbers in PHP code affect the functionality of a script?

Using quotation marks for numbers in PHP code can turn the numbers into strings, which can lead to unexpected results when performing mathematical operations or comparisons. To avoid this issue, always use numbers without quotation marks when working with numerical values in PHP.

// Incorrect usage with quotation marks
$number = "5";
$result = $number + 2; // This will concatenate the strings instead of performing addition

// Correct usage without quotation marks
$number = 5;
$result = $number + 2; // This will correctly add the numbers