<?php
echo 'this is a test five seconds minus three seconds equals: ' . 5 - 3 . ' seconds' . "\n";
echo 'this is a test five seconds minus three seconds equals: ' . (5 - 3) . ' seconds'. "\n";
echo 'this is a test five seconds minus three seconds equals: ' , 5 - 3 , ' seconds'. "\n";
?>

PRODUCES:

-3 seconds (What the hell happens here?  I thought . and , were identicle? besides the , was faster to concatenate?
this is a test five seconds minus three seconds equals: 2 seconds
this is a test five seconds minus three seconds equals: 2 seconds