mettere un ID

//mio
function prezzo_minimo_meta_box_render( $post ){
  $number = get_post_meta( $post->ID, "function_prezzo_primo",true );
 $number2 = get_post_meta( $post->ID, "function_prezzo_primo_dom" ,true);
// Get the number and display it in a numeric field
if( !empty( get_post_meta( $post->ID, "function_prezzo_primo", true ))) {
$output= '<div><input type="number" value="'. round( $number/7, 0 ) .'" placeholder="prezzo/notte in euro" /></div>';
echo "$output";
} elseif ( !empty( get_post_meta( $post->ID, "function_prezzo_primo_dom"))) {
$output= '<div><input type="number" value="'. round( $number2/7, 0 ) .'" placeholder="prezzo/notte in euro" /></div>';
echo "$output";
}  else {$output= '';
}
}