Lesson 8
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Make sure you know you know your basic multiplications of one-digit number (like 8 x 7) with “Numbers Jugging - Times without the Tables.”
Now that you are a whiz with almost all the digits times three, we’ll learn the rule for the ambiguous digit 6, to finish up with multiplication by three.
This is the rule for the ambiguous digit 6:
When you see a six, keep looking to the right of it.
- If the digit to the right is higher than 3, you will have to carry a 2 higher up the chain.
- If the digit to the right is lower than three, there will be a carry of 1.
- If the digit to the right is 3, you must keep looking right to see if the next digit is higher or lower than 3,
- and if that digit is a 3, you must keep looking, and so on, until you find a digit that is higher or lower than three.
There is normally a carry of 1 with 6*3, but if it’s followed by a number higher than three, the carry will be 2.
So get our your deck of cards and get to work multiplying 3 by all the digits. Use one of each of the cards, except for the 3s and the 6s; use all four of both of them.
Or, if you would like a worksheet of large numbers (with all the digits and lots of sixes) to print out and practice multiplying by three with, click here. The answers are included on the sheet, so fold it over in half (on the dotted line) to hide the answers as you do the problems.
Tomorrow we’ll do some practicing with multiplication by 2 and 3, and the next day, we’ll cover some things that you might have already noticed, but didn’t know there were rules for.
The podcast for this lesson is not up yet. If you click on the podcast icon, you will get an error message. The podcast will be up by the end of the first week of March.
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Comment by Linette
HI Math Mojo. when will the podcasts be up for the later lessons. 7 and onwards? You mention on the site that it will be up end March?
please advise as I go into your site every other day to chek if it is up. I really would like to see it soon?
Comment by Brian
Sorry I’ve been so lame about the podcasts.
Here’s the scoop, according to the Math Mojo Monthly Newsletter, which is finally going out this week,:
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What’s up with “Eating Math for Breakfast’?
Some of you may have signed up for the “Eating Math for Breakfast” podcasts at the Math Mojo Chronicles. You may have noticed that I have not continued them past multiplication by 4. That is because, to put it mildly, the podcasts were a bit boring. The Idea was a good one, but the subject matter doesn’t lend itself to just an audio podcast, so I am working on an enhanced podcast (with visuals) of the same material. The visuals will help to make learning the material easier, as well as more interesting.
Unfortunately, that doesn’t lend itself to listening to them in the morning, as a family. So I will begin a more interesting, purely audio podcast soon. I’ll let all subscribers to “Eating Math for Breakfast” know when both sets of podcasts are ready. If your a subscriber, you’ll automatically get an e-mail when they’re ready to launch.
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But since you took the time to ask, I’ll get to it by tomorrow, with the first new, enhanced podcast. Do you have iTunes? That will make it much easier to access it, and when it comes out, it will have a subscription
Button, so when each new one comes out, it will automatically be sent to your iTunes.
Thanks for the encouragement for me to get back on the ball with this!