PHP is a type less language, which can seamlessly manipulate variables containing any sort of data.

However, forgetting about the underlying types can make your application slow and potentially open to security vulnerabilities.

Forcing correct type via casting
<?php
    $_GET['n_entries'] = (int) $_GET['n_entries'];
?>
Type conversion prevents things like SQL injection due to unexpected input. It also optimizes the application by providing PHP with a type it expects, rather having to internally perform type conversions each time the variable is used.