How can the PHP script be modified to allow for variable numbers of file uploads, rather than a fixed number of 4?

To allow for variable numbers of file uploads in a PHP script, we can modify the script to dynamically handle multiple file uploads by iterating through the $_FILES array. We can check for the number of files uploaded and process each file accordingly within a loop. 

```php
<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $total_files = count($_FILES['file']['name']);
    
    for ($i = 0; $i < $total_files; $i++) {
        $file_name = $_FILES['file']['name'][$i];
        $file_tmp = $_FILES['file']['tmp_name'][$i];
        $file_size = $_FILES['file']['size'][$i];
        $file_type = $_FILES['file']['type'][$i];
        
        // Process each file here
        // Example: move_uploaded_file($file_tmp, 'uploads/' . $file_name);
    }
}
?>
```

In this modified PHP script, we first count the total number of files uploaded by accessing the 'name' index of the $_FILES array. We then iterate through each file using a loop, accessing the file details such as name, temporary location, size, and type. You can process each file as needed within the loop, such as moving it to a specific directory or performing any other operations.

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