Long Multiplication

In this dyslexia blog article there are some tips and advice on long multiplication.

Being able to recall basic multiplication facts is essential for success with long multiplication, therefore it is crucial you make sure your child practices their times tables on a regular basis. Games are a good way to motivate them to learn them !!

Students who have dyslexia will often have a weakness in their working memory. As a result it may be difficult for them to rely solely on mental calculations when solving math problems.The dyslexic student may often forget what they are doing and lose their place . In long multiplication ,of course,there is more of a risk that there will get muddled up since the numbers that they are dealing with are bigger.

When they are are doing long multiplication problems teachers and parents should encourage children to write down every step, including carrying numbers.They should also preferably use scrap paper to help them in their calculations.

Common errors made :

Students make mistakes because they haven’t kept their columns straight. Make sure they line up their numbers correctly and also encourage correct spacing. It is advisable to use squared paper at all times for maths calculations to prevent this problem.
Unfortunately sometimes teachers don’t leave enough space for workings out on worksheets and test papers and this creates problems !!

Forgetting to ‘carry’ numbers A good way to remember the carry number is to write it in a circle.

Forgetting to write down a zero eg :

110
x69
990
660 should be 6600
=1650 ( answer should be 7590 )

You could consider teaching your child alternative methods to solve long multiplication problems. One such method is long multiplication using key facts. This method is recommended by Steve Chinn who is one of the leading experts in the area of dyscalculia. With this method your child only needs to know how to double and half numbers and multiple by 10 to get the correct answer.

Long Multiplication using key facts

E.g 78 x 17

1) First set up an easy multiplication table with the key facts :


1 x 17 = 17
2 x 17 = 34
5 x 17 = 85
10 x 17 = 170
20 x 17 = 340
50 x 17 = 850
100x 17 = 1700

1x 17 is easy to find = 17.
To get 2 x 17 just double 17.
After workout 10 x 17 = 170 .Now you can easily find 5 x 17 – just half 170. ( 85 )
For the answer to 20 x 17 double 170 .
100 x 17 is easy just add a zero to 170 ( 10 x 17=170).
For 50 x 17 half the answer to 100 x17 = 1700 ie 850.

2)After find the easy numbers ( or partial products ) in 78 .

78 = 50 + 20 + 5 + 2 + 1

3) After add up these partial products :
50 x 17 = 850
20 x 17 = 340
5 x 17 = 85
2 x 17 = 34
1 x 17 = 17

Answer 78 x 17 = 1326

In Turkey however unfortunately some teachers are reluctant to teach alternative methods of doing maths calculations. Also this method does require more space on the paper for the workings out. In many cases worksheets and test papers provide little space for students to use .It is assumed a lot of workings out will be done mentally. Teachers here in Turkey need to try to be more flexible in their approaches in order to accommodate all children. I would recommend everyone to look at Steve Chinn’s books for more ideas regarding maths.

NINE TIMES TABLE

Nine times table trick

Dyslexic children, as I have mentioned before often struggle with learning the multiplication tables. Here is a neat way to help them find the answers for the 9 times table.

For example 9 x10

First take 1 away from 10

10- 1 = 9

Then take the answer 9 away from 9

9- 9 = 0

So the answer is 90

Another example : 9 x 7

First take 1 away from 7

7 – 1 = 6

After take the answer 6 away from 9

9-6 = 3

So the answer is 63

Try it out !!!

LATTICE MULTIPLICATION

Lattice multiplication

Very often children with dyslexia or learning disabilites may find problems with the traditonal method for long multiplication.This is because it relies heavily on the working memory .

If your child is struggling with multi-digit multiplication then lattice multiplication is a good tool to try out as it will help them to gain confidence.

Lattice multiplication is a method of multiplying large numbers using a grid. This method breaks the multiplication process into smaller steps, which some students find easier. Digits to be carried are written within the grid, making them harder to miss.



Here is an explanation of the lattice multiplication method :


Let's multiply 216 x 32. First write the 216 across the top, and the 32 down the right side of a 3x2 rectangle. ( see above diagram )

Now fill in the lattice by multiplying the two digits found at the head of the column and to the right of the row eg 6x3 .
When the partial product is two digits, the first (10's) digit goes above the diagonal and the second (1's) digit goes on the lower right of the diagonal. If the partial product is only one digit, a zero is placed in the triangle above the diagonal in the square.

At this point, we have the multiplication done. Now we add along the diagonals beginning in the lower right to get the final product. Any "carries" when adding are illustrated outside the rectangle.

(This explanation is from : http://mathforum.org/ )

To watch a demonstration video of Lattice multiplication go to :
Mary Bryan Elementary School : Maths videos
http://mb.msdpt.k12.in.us/Math/Algorithms.html

Also :
http://blog.syracuse.com/video/2008/06/everyday_mathematics.html

For blank lattice grids go to :
http://www.superteacherworksheets.com/lattice.html

http://www.mathwire.com/numbersense/mult.html

http://www.skillsworkshop.org/n/e3l1l2latticepaper.pdf










.

FINGER TABLES

FINGER TABLES - 9 TIMES TABLE

Your child may be struggling with multiplication because he is dyslexic.Here a really neat way to teach your child the 9 times tables using their fingers !!

1. Hold your hands in front of you with your fingers spread out.
2. For 9 X 7 bend your seventh finger down. (9 X 3 would be the third finger etc.)
3. You have 6 fingers in front of the bent finger and 3 after the bent finger
4. Thus the answer must be 63 ( see diagram above )
5. This technique works for the 9 times tables up to 10.

ITS VERY EASY AND YOUR CHILD WILL PICK IT UP QUICKLY!!

A MULTIPLICATION GAME

YOU CAN USE ORDINARY PLAYING CARDS TO HELP PRACTICE MULIPLICATION FACTS !!

Dyslexic children often find difficulty learning their times tables They will however learn their facts much more quickly if you play games with them on a regular basis , as it makes learning more fun. Below is one example of a game you could try using playing cards !!

Remove the Kings and Queens from a deck of cards.

Use a marker pen to write an "11" on each Jack and a "12" on each Ace.

Shuffle the cards and then take it in turns to flip over two cards.

Your goal is to say the two multiplication facts that go with the pair of cards eg a three and and five =‘15’ .You keep the cards if you are the first one to say the answer.

The one with the most cards is the winner.

If you wish, focus on the facts that give your child the most trouble. You could give a small reward if your child gets a certain number of cards.