2.239 WARNING
When you use 'dozen', 'hundred', 'thousand', 'million', or 'billion' they remain singular even when the number in front of them is greater than one.
2.240
You can use 'dozen', 'hundred', 'thousand', 'million', or 'billion' without 'of' in a less precise way by putting 'several', 'a few', and 'a couple of' in front of them.