Here are some of the mathematical tricks.

harsh15

Here are some of the mathematical tricks.

Hope it will help you.

*Multiply Up to 20X20 In Your Head

In just FIVE minutes you should learn to quickly multiply up to 20x20 in your head. With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator.

I will assume that you know your multiplication table reasonably well up to 10x10.

Try this:

Take 15 x 13 for an example.
Always place the larger number of the two on top in your mind.
Then draw the shape of Africa mentally so it covers the 15 and the 3 from the 13 below. Those covered numbers are all you need.
First add 15 + 3 = 18
Add a zero behind it (multiply by 10) to get 180.
Multiply the covered lower 3 x the single digit above it the "5" (3x5= 15)
Add 180 + 15 = 195.

*To multiply any two digit number by 11:

For this example we will use 54.
Separate the two digits in you mind (5__4).
Notice the hole between them!
Add the 5 and the 4 together (5+4=9)
Put the resulting 9 in the hole 594. That's it! 11 x 54=594

The only thing tricky to remember is that if the result of the addition is greater than 9, you only put the "ones" digit in the hole and carry the "tens" digit from the addition. For example 11 x 57 ... 5__7 ... 5+7=12 ... put the 2 in the hole and add the 1 from the 12 to the 5 in to get 6 for a result of 627 ... 11 x 57 = 627

*The 11 Rule Expanded

You can directly write down the answer to any number multiplied by 11.

Take for example the number 51236 X 11.
First, write down the number with a zero in front of it.

051236

The zero is necessary so that the rules are simpler.

Draw a line under the number.
Bear with me on this one. It is simple if you work through it slowly. To do this, all you have to do this is "Add the neighbor". Look at the 6 in the "units" position of the number. Since there is no number to the right of it, you can't add to its "neighbor" so just write down 6 below the 6 in the units col.
For the "tens" place, add the 3 to the its "neighbor" (the 6). Write the answer: 9 below the 3.
For the "hundreds" place, add the 2 to the its "neighbor" (the 3). Write the answer: 5 below the 2.
For the "thousands" place, add the 1 to the its "neighbor" (the 2). Write the answer: 3 below the 1.
For the "ten-thousands" place, add the 5 to the its "neighbor" (the 1). Write the answer: 6 below the 5.
For the "hundred-thousands" place, add the 0 to the its "neighbor" (the 5). Write the answer: 5 below the 0.
That's it ... 11 X 051236 = 563596

*Square 2 Digit Number: UP-DOWN Method

Square a 2 Digit Number, for this example 37:

Look for the nearest 10 boundary
In this case up 3 from 37 to 40.
Since you went UP 3 to 40 go DOWN 3 from 37 to 34.
Now mentally multiply 34x40
The way I do it is 34x10=340;
Double it mentally to 680
Double it again mentally to 1360
This 1360 is the FIRST interim answer.
37 is "3" away from the 10 boundary 40.
Square this "3" distance from 10 boundary.
3x3=9 which is the SECOND interim answer.
Add the two interim answers to get the final answer.
Answer: 1360 + 9 = 1369

THAT?S IT.

By the way its my first article, I will submit more later .

Hope you liked it.

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