Do you have a child who needs a confidence-boost in school? Imagine if your child knew the multiplication tables up to 20. It would make him or her seem like a genius compared to most school children who have problems even remembering 7x 8! If you are like most people, you probably think that memorizing the times tables to twenty would be a heck of a chore. It would! It would be crazy!
I feel sorry for anyone who's already done that when they read ahead and learn the method to get the answer to any multiplication problem with whole numbers between 10 and 20, fast, with no need for memorization. They would have saved weeks of boring, rote memorization if they used this method instead.
Here's how you do it:
Let's say you are multiplying 12 x 17.
Step 1) Add the ones column of either of those numbers to the other number. In this case you could add either 7 + 12 or 2 + 17. (Both would give you the same result, namely 19). Put a zero after it, to get 190.
Step 2) Get the product of the last digits of each of the original numbers (that would be 2 x 7, which would give you 14).
Step 3) Add the two numbers you got. In this case that would be 190 + 14. You'd get 204, and you'd be done, because 12 x 17 = 204.
That's how easy it is, and it works for any numbers between 10 and 20!
Try 19 x 14.
1) 19 + 4 = 23. 23 with a zero at the end is 230. 2) 9 x 4 =36 3) 230 + 36 = 266, which is the correct answer. Piece of cake!
Please, please, please don't ever write anything down when you do this! It wlll defeat the whole purpose of this method. Writing down things that a child's mind should be able to do is like training yourself to use crutches when you don't need them. The whole point of this is to trust your brain, and learn to do simple math mentally.
Here are some more examples. Once you have practiced them, you should become fast enough to amaze anyone, especially an elementary school teacher. A third-grader should be able to do these with ease in a short time, and become the "Einstein" of his or her class.
18 x 13 15 x 16 19 x 18 17 x 14 12 x 16
You may come across instances where you will have to carry. You will automatically understand how to do that if you pay attention.
Remember, you are trying to boost confidence, and you can't do that unless you have the basics down. With the basic multiplication tables "in your bones," this way to multiply numbers up to 20 can be a "reputation-maker."
Of course, if you or someone you know (your child or student, maybe?) hasn't totally mastered the "multiplication tables," the above method won't do you much good, will it? You'll be happy to know that there is a fool-proof, easy way to teach or learn the basic times-tables in minutes, and it's even easier than the the method for multiplication of 10 through 20. Learn to Multiply with this Easy Method, now.
Brian Foley (a.k.a. "Professor Homunculus") is the creator and web manager of Math Mojo and The Math Mojo Chronicles. He's presented his Math and Magic programs at schools, corporations, and other facilities throughout the U.S. and Europe.
