Archive for: April 2008

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To check multiplication of single digits by longer numbers with playing cards:

We’re going to use what I call “numbers crunching” to check. That is the same as using the nines-remainders. You do know how to get the nines-remainder of a number, don’t you? It’s very simple, but it takes a bit of explaining.

It also pays to know why checking with nines-remainders works. Both of those things are beyond the scope of this article, but I’m working on a booklet and a video about how to check your answers for all of the basic operations of math using “number crunching”. There are lots of tips and shortcuts that make this method absolutely simple and effective. Let me know if you’re interested by using the “Contact” box near the upper right hand corner of this page.

(This video will be re-edited and uploaded by the end of Wednesday, April 30)

If you know about crunching, you’ll be interested to know that practicing with cards like this is perfect for checking with crunching. It turns out that if you crunch all the digits from zero to nine, you get a crunch number of 0.

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Math Mojo has got some surprises for you. New lessons on how to improve your basic math skills, and videos! Professor Homunculus is getting his Video Mojo workin’ to bring you some great new stuff.

The first set of videos will be about how to practice multiplication using playing cards. So grab a deck of cards and let’s get going!

First, take out all the Spade cards from the deck - we’ll only be using those. Then, remove the court cards (the Jacks, Queens and Kings) from those cards. Consider the Ten to be a zero and the Ace to be a one.

Now you’ve got 10 cards, which represent the digits zero through nine.

Shuffle the cards. Now decide, in your mind, which digit you’d like to multiply by.

Deal the cards, face up, on the table so that you can see the faces of all the cards.

Get out a piece of paper and a pencil.

Depending on how advanced you are at multiplication, start at either the right (if you multiply the “school” way) or the left (if you know Math Mojo) of the spread deck, and start multiplying, writing only the answer (not the carries - never write the carries!)

In the video, we’ll be multiplying all the digits from 0 to 9, by 3. It’s simple to start with 3.

After you learn how to do it, try multiplying the cards by the other digits.

We’ll multiply by some higher digits in future videos.

You may have noticed that I don’t know my left from my right in this video. My bad!

Tomorrow we’ll practice checking, using this same example.

Something’s been on my mind for a long time. It’s the whole “public school atmosphere” thing.

I didn’t generally like school when I was a kid. I guess I went to pretty good schools, as far as schools go. I liked a lot of my teachers. I just didn’t like the “set-up.” I thought that whoever designed the whole process must have been a bunch of ignorant, arrogant jackasses.

Year after year, teachers and students complained about the same things. Some were reasonable, some weren’t.

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Surely most readers have had thoughts and observations about boys’ and girl’s differences concerning their typical learning strategies.

A reader (Susan G.) has been corresponding with Math Mojo for a week or so, and I’ve noticed that she’s made some great observations. She’s also written a e-book on word problems. I’m in the process of reading it, and it looks right-on-target. It will be a resource that teachers and home-schoolers will want to have.

I’ll be writing more about it in the future. In the meantime, if you want to find out more about it, please shoot me an e-mail (use the contact box on this page) asking about it, and I’ll put you in touch with her.

Susan had been kind enough to offer some of her expertise about education in general, and she’s been one of the readers who’s taken my request for proofreading to heart; she’s pointed out some typos in Math Mojo materials, which I’ll be correcting a.s.a.p. (Thanks for the heads-up on this stuff, Susan!)

She’s kindly given me her permission to publish some of the thoughts we’ve been sharing about math-ed.

Here’s and excerpt from a recent correspondence we’ve had:

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