In what scenarios would it be necessary to differentiate between numbers and digits when working with PHP?

When working with PHP, it may be necessary to differentiate between numbers and digits when performing calculations or manipulations on numerical data. Numbers refer to the mathematical concept of quantities, while digits are the individual characters that make up a number. It is important to distinguish between the two when, for example, validating user input to ensure it consists only of digits or when converting a number into its individual digits for further processing.

// Example code to differentiate between numbers and digits in PHP
$number = 12345;

// Get the individual digits of the number
$digits = str_split((string)$number);

// Output the individual digits
foreach ($digits as $digit) {
    echo $digit . " ";
}