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How to learn and teach multiplication

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Think Outside the (Multiplication) Tables

 

Ever get the feeling that there are secrets to life that no one is telling you? Take it from a magician, there are. Not the kind that you may think, though.

Here is one that scares the pickles out of me - you know that "tables" stuff they tortured you with in school? Well, not only are they not the only way to learn how to multiply, they are nowhere near the best, the easiest, the most efficient, the most effective, and they sure as poop aren't the most fun.

Why do they teach it that way? Who knows? Who cares?

Who wants to learn a better way? Read on...!

Thinking about how to learn to multiply 

Starting out

The standard method in western countries is to insist that you stare at some page filled with "the multiplication table" and "Just shut up and memorize it!"

Forget that, entirely! First of all, we are usually not taught any meaningful way to memorize things. The default method that most people have is untrained, and pretty shakey, at best.

My Idea is to use an active method that forces you to use your brain a bit. When you do this, your brain (which is smarter than your teacher) creates new mental pathways. When it does it often enough, those pathways are "etched" deeper into your brain, so they become "highways." Remember, though, that this is just a metaphor, and isn't quite the way your neurology works, but it makes sense to us as a metaphor.

If you practice something enough, it becomes easier. If you stare at something passively long enough and often enough, it will create pathways. But if you actively create the pathways, they will be made sooner and deeper.
And if you use a bunch of different ways, you will create wider, deeper paths.

So if you find ways to calculate the multiplications, instead of using passive memorization, you will be more successful.

The simplest (not necessarily the easiest or the best) way to calculate your multiplications, is to do the exact operation that it is, which is namely repeated addition. In other words 6*4 becomes 4+4+4+4+4+4.

(It is important to know that although multiplication of whole numbers is essentially repeated addition, the meaning of multiplication does not end there. Like most things, the more you learn, the more you can understand, and once you learn basic multiplication and arithmetic you can go on to learn very interesting properties about multiplication that go beyond simple repeated addition. But when you are starting out learning, "multiplication is repeated addition" is a good rule of thumb.)

If you do your multiplications that way often enough, your brain starts thinking, "Hey, this is a pain in the neck. I can do it, of course, but there must be a better way. So the next time we do this, I'm going to store the answer in my memory, so that after that I won't have to go through this tedious process anymore."

That all happens on a subconcious level, you understand. It's a great talent, that brain of yours.

If you need an illustration of how this works in other fields, take someone who is learning to shoot baskets. If he has a good coach, the coach tells him all the things he needs to know, like how to bend at the knee, use the wrists, etc.

Now, the player can just listen to the coach, make notes of what he's saying, and repeat those instructions to himself over and over, with no physical effort.

But you and I know that at some time he's going to have to go out and shoot some hoops. And only by repeated trial, does his body memorize the actions, and streamline the process. That's because the body and the brain don't want to work too hard forever.

How to learn Basic Multiplication of single-digit-numbers 

These are often called the "multiplication tables" or "multiplication facts" but both of those terms are misleading.

Somehow the term "multiplication tables" gives one the impression that there are some "magical tablets brought down from the mountain," like they are the only way to learn.

The "tables" are simply a list of what happens when you multiply a set of numbers by each other, they are not the multiplications themselves. (Give that a chance to sink in - it's deeper than you may think.)

The "tables" are like a roadmap, but they are not the road. If you teach a kid that the tables are the only way to learn, you are depriving him from experiencing real multiplication. Multiplication is about manipulating numbers, or amounts. Deep understanding of simple multiplication is a necessary part of developing numeracy (the ability to understand and work with numbers).

The term "multiplication facts" is also a really bad Idea to inculcate young minds with. Not only does it suffer from the problem mentioned above, but it also gives the impression that they just happen to be "facts" that exist outside of you. Yes, they are facts, but they exist inside of you. You can reconstruct them simply by using your mind. They are not like facts like, say, historical facts like "The Magna Carta was signed in 1215." That is something you cannot directly experience, and must simply learn as a "fact." (Actually, that is not strictly true either, just ask a real historian.)

See, learning something strictly as a "fact" makes you feel like a victim of that fact, rather than a participant. Direct, or indirect experience with something makes it so much more alive, real, and actually fun.

So the best ways to learn math are not with flash cards, silly rhymes, obnoxious cartoon characters or other methods that distance a child from direct experience of numbers and how to use them. (Don't even get me started about the evils of calculators...)

The best ways to learn math are ways that have you use actual math. Imagine that! Learning how numbers relate to each other is the way to go. I'm biased, of course (because I wrote it) but I think "Numbers Juggling - Times without the Tables" is the best explanation of how to learn basic multiplication that works for most people, especially the ones who think the "tables" are a pain.

Numbers Juggling (Times without the Tables) 

Think outside the "Tables"

I wrote this e-book because I was disgusted with the way we are normally taught how to multiply. This booklet will open your eyes to a new world. You will learn a method to teach any child basic multiplication of single-digit numbers (what we normally call "the times tables" or "multiplication facts" in about two minutes.

The booklet then goes on to show how to "lock this knowledge in."
It also comes with seven e-mail lessons that will show you the math behind the method, so you can actually understand and show your child why it works!

I truly believe that every parent and teacher should know what is taught in this booklet, so every child can have a meaningful, helpful method for dealing with this important subject.

The e-booklet is only $9.95. That's a small investment to give you or your child an advantage in this basic life-skill.

You can order "Numbers Juggling - (Times without the Tables)" now.

How to mentally multiply any whole number by a repunit (Part 1 of 3) 

What the heck is a repunit? A repunit comes from the words "repeating unit," in other words, it is a number made up of repeating ones, like 11, or 111,111.

Just as a refresher, a whole number is zero and all the counting numbers from 1 on, forever. The whole numbers are 0,1,2,3,4,5... (The three dots mean "and so on).


Now, there is a really good interactive lesson on how to multiply any whole number by 11, mentally, at this page at MathMojo.com. You should learn that before reading further.

Helpful Math and Multiplication links 

Math Mojo
This is my main website. It was conceived to help people who think they suck at math. There are lots of mental math tips, and encouragement for people who know they are smart, yet have struggled to learn math.
The Math Mojo Chronicles
The official weblog of MathMojo. Posts about math and critical thinking. Irreverant, but relevant!
Math and Magic
The skinny on how to use thinking methods of magicians to learn something useful, and fun.
Forget those silly "add your age to the number of coins in your pocket, divide by 5, multiply by ... etc" tricks.
This is about using magic to accomplish something that means something!
Learn2multiply
An amazing method to learn the "tables", and an amazing way to teach it. If you know someone who needs help with basic multiplication, this is it.
Math Doesn't Suck
Lens about Danica McKellar's new book, "Math Doesn't Suck."
The actress/mathematician who played "Winnie" on "The Wonder Years" has written an inspirational and educational book to help middle-school girls respect and improve their brains, while still being able to remain feminine and popular.

Great Math Newsletter for all Ages (FREE!) 

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How to mentally multiply any whole number by a repunit (Part 2 of 3) 

Back already? Good, now let's try any number times 111. Let's use 674 * 111



  1. Start at the left of the multiplicand (that's the 674) and pretend there are two zeros behind it and in front of it, making it 0067400. Now add the final three digits, (in 0067400 that would be 4+0+0) and write the sum (4) beneath the 4 in the 0067400 . That's the digit in the units column of the product. (The product is the answer.)


  2. Next, add the three digits that start second from the end of the multiplicand (in 0067400 that would be 7+4+0 = 11) and write the units digit(1) of that number to the left of the last number you wrote, giving you 14 so far. Keep the tens digit of that number in your head - you are going to carry it to the next addition.


  3. Now add the three digits (plus the carry) that start third from the end of the multiplicand (in 0067400 that would be 6+7+4+1 = 18) and write the units digit of that number (8) to the left of the last number you wrote, giving you 814 so far. Keep the tens digit of that number in your head - you are going to carry it to the next addition.


  4. Now add the three digits (plus the carry) that start fourth from the end of the multiplicand (in 0067400 that would be 0+6+7+1 = 14) and write the units digit of that number (4) to the left of the last number you wrote, giving you 4814 so far. Keep the tens digit of that number in your head - you are going to carry it to the next addition.


  5. Now add the three digits (plus the carry) that start fifth from the end of the multiplicand (in 0067400 that would be 0+0+6+1 = 7) and write the units digit of that number (7) to the left of the last number you wrote, giving you 74814 so far. There is no tens digit to carry this time. You are finished.

How to mentally multiply any whole number by a repunit (Part 3 of 3) 

If the multiplicand had been longer, say, 876,346,974, it would still work the same way. You would just continue on until you ran out of digits.


If you learned this, and the original lesson for multiplication by 11 at MathMojo.com, you must see a pattern by now:



  • If your repunit has four digits, you put three imaginary zeros in front and behind, then, starting at the end, add four digits each time.


  • If your repunit has five digits, you put four imaginary zeros in front and behind, then, starting at the end, add five digits each time.


  • and so forth.

  • P.S. Are you aware that squaring any repunit (at least up to nine digits) will give you a palindrome? Try it.


    Some people like to complain that math is so uninteresting because "all you do is the same thing over and over, and get the same answers, etc." I feel bad for them. They don't get it that although, in arithmetic at least, any problem has only one answer, there are lots of ways to get there, and only the one you learned in school is boring.

    What are you interested in? 

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    Great Math Books for Every Home 

    Personally Recommended by Professor Homunculus

    The Number Devil: A Mathematical Adventure

    From the amazon.com review: "...introduce basic concepts of numeracy, from interesting number sequences to exponents to matrices. Author Hans Magnus Enzensberger's dry humor and sense of wonder will keep you and your kids entranced while you learn (shhh!) mathematical principles."
    Professor Homunculus sez: "If you are helping a child learn math, this book is a MUST!"

    Amazon Price: $12.92 (as of 10/12/2008)

    Playing with Infinity: Mathematical Explorations and Excursions

    From the a reader's review on amazon.com: "This book explains the why's behind math from principles as basic as counting to as complicated as series, geometry, and even some calculus principles. It is written in a conversational tone with lots of pictures (yes, and numbers). Each chapter builds upon the last, and it is easy to follow (though sometimes dense). It was my first "fun" math book and is still by far my favorite."
    Professor Homunculus sez: "I couldn't agree more!"

    Amazon Price: (as of 10/12/2008)

    Mathematics for the Million/How to Master the Magic of Numbers

    This book is a classic. It was the book that launched the intellectual self-improvement movement in America. It is perhaps the best book on general math ever written. Hogben takes you from the birth of mathematics to calculus in a lucid, human way. Even if you use only this one book, you will not only understand everything you will need for all of high-school math, and most of college math, but you also have a good basis for understanding the spirit of mathematics. H.G. Wells called it, "A great book, a book of first-class importance."

    Amazon Price: $12.21 (as of 10/12/2008)

    Reader Feedback 

    Let me know your experiences or concerns about learning multiplication.

    SemperFidelis

    I'll show this one to my daughter the teacher!
    Blessed by a Squid Angel today! :)
    Colleen ~ www.squidoo.com/squid-angel

    Posted August 13, 2008

    nadiasorkin30

    I really like your suggestions for math books. I intend to pick one of them up today. Thanks for the hints!

    Posted August 11, 2008

    girl

    Thanks for sharing your gift of knowledge with us...

    Posted July 30, 2008

    PotPieGirl

    5* - As a mom, this is GREAT information! As a lensmaster, this is a wonderful lens!

    Nice work =)

    Posted June 23, 2008

    sidvicious2008

    Nice lense. I appreciate your effort.

    Posted May 29, 2008

    eugenia francis

    Check out my workbook, Teach Your Child the Multiplication Tables, Fast, Fun & Easy with Dazzling Patterns, Grids & Tricks. My son had difficulty with rote memorization, so I developed a method based on patterns. Patterns enhance recall. Eugenia www.TeaCHildMath.com

    Posted February 22, 2008

    Evelyn_Saenz

    Thank you for sharing such a great lens. Playing games is a great way to practice and learn math. Using a Hands-On Approach to learning is the best way for children to truly grasp mathematical concepts. I look forward to reading more of your lenses.

    Posted February 17, 2008

    SteveRogers

    Damn, this makes so much sense. Why don't schools "get it?"

    Best of luck with your lens and mission,

    Steve

    Posted February 04, 2008

    Max_Nix

    Hey, that's pretty good! Got more tricks (I mean "magic")?

    Max Nix

    Posted October 01, 2007

    Sal

    Cool, cool, cool! I never knew that magic was really a serious art!

    Posted October 01, 2007

    puppetess

    This looks like a great site to send homeschool kids to. I'll recommend it to my friends. Thanks for the good tips.

    Posted September 20, 2007

    Chris Small

    Great lens, Brian! I'm going to teach my kids using this stuff. Thanks!

    Posted August 12, 2007

    Lance Boyle

    Interesting. Do you also have hints for division? I think I can use this stuff to help my middle-school students who didn't "get" multiplication in elemementary school.

    Posted August 12, 2007

    klapskie

    thanks for all the tips you've written, this can help people of all ages.Giving you 5 stars. :)

    Posted July 26, 2007

    CateSanderson

    Wow Brian! I'd say you certainly have put a lot of work into your lenses. How do I see my own lens?

    Posted June 26, 2007

     
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    Homunculus

    About Homunculus

    Hi,

    My name is Brian Foley (a.k.a. "Professor Homunculus" at the mathmojo.com site).

    I am not a "math guy" and never was. I don't care about the school subject of math. I never passed math in school. Only a fluke kept me from not getting a high-school diploma because of failing math in all grades but one (geometry - had a great teacher) all my life.

    It's a long story, but I learned about all the math I know through magic books when I was in my thirties. OK, since then I've read other math books, but they haven't been textbooks and they sure as hell haven't been those touchy-feely idiot math books with consumer brand names in them.

    I've done magic in Europe for 18 years, and in the States for about 20 years. I'm from New York state. From Brooklyn, to Lawn Giland, to the Upper Catskills, where my heart is.

    I was a street magician (before David Blaine was born, I believe), a corporate magician, and now I'm a math magician, among other things.

    The immediate mission is to take away the stigma and fear of math that many people (especially Americans) have.

    I hope to do it with books and lectures, and my websites, MathMojo.com and The MathMojo Chronicles.

    My interest is you, because the more people feel comfortable with the beauty, wonder and magic of math, the more people feel comfortable with life, logic, and critical thinking.

    That basically means less people feeling rotten about their minds, themselves, and life in general.

    It means less people making idiotic decisions, like thinking they are not smart enough to learn math well.

    Everyone can.

    You can.

    Let's go!

    Homunculus's Pages

    See all of Homunculus's pages