What's left? 3,6,7 and 8:
The threes are like the nines; there are 3 groups of 3 in every 9.
Here are links to videos as well as the powerpoint slides I made first. You'll have to hit the "back" button right now to get back to this page.
On Repl.it these are relative links and their relatives aren't here (I'm not going to upload all those videos).
There will be more quizzes with different kinds of practice.