# Multiplication (Special Cases)

Multiplication Simplification Approximation

Hello readers, as you know yesterday we have discussed some Vedic methods of multiplying by 2, 3 and 4 digit number.  Today we will discuss some special cases of Multiplication Simplification Approximation that will help you to enhance your speed. The tricks which we are going to use will help to you to do multiplication by just seeing that numbers or by using very less paperwork.

Let’s start learning some interesting tricks to assure our success.

• MULTIPLICATION BY 5

To do multiplication by 5, we will:

• First, we will multiply the number by 10 (or out One Zero to the right of the number)
• Than in second step, Divide the number by 2 or HALF the number

Seems easy no?

Let’s  see this with the help of Example

Example

42568×5 =? So Rule is:

RULE – MULTIPLY ME BY 10 AND HALF ME (÷2)

• MULTIPLICATION BY 9

To do multiplication by 9, we will :

• First, multiply the number with 10
• And than in second step, Subtract the number itself from the result obtained after multiplying the number with 10

Let’s see this with the help of example:

Example:

2142 × 9 =? So Rule is :

RULE – MULTIPLY ME BY 10 AND SUBTRACT THE ME ITSELF

• MULTIPLICATION BY 11

We all know how to multiply by 11. But not all of us know how to multiply by 11 just by seeing the numbers. Right, you read it right. By this trick you do not feel any need to write anything and can solve the multiplication.

We will explain this with the help of example

Example:

12432 × 11 = ? • First write ZERO or imagine ZERO in front of the given number
• Than start from the right hand side digit i.e. 2, and write as it is to the answer because there is no number on its right side.
• Than add the 2 to the next number which is 3; and write 5 to the answer.
• Repeat adding the next numbers till the digits end and you will get the answer.

Isn’t this is very easy trick ?

So Rule is :

RULE –  “ADD MY RIGHT NEIGHBOUR”

• MULTIPLICATION BY 12 The trick to multiply by 12 is bit similar to multiplication by 11.

Let’s see how to do multiplication by 12.

• First write ZERO or imagine ZERO in front of the given number
• Than starting from the right hand side digit, multiply the number with 2 and write the number in the answer i.e. 3×2 = 6
• Than, come to the next digit (starting from right hand side only) and multiply the digit with 2 and add its right neighbour i.e. 1×2 + 3 = 5.
• Repeat doubling each digit and adding its neighbour till last digit(as shown above) and you will get the answer.

So Rule is :

RULE – DOUBLE MY EACH DIGIT IN TURN AND ADD MY RIGHT NEIGHBOUR

• MULTIPLICATION BY 13

Multiplication by 13 is also similar to 11 and 12. Here we will treble each digit i.e. multiply each digit wil 3 and then add its neighbour.’

Example:

2134 × 13=? • First write ZERO or imagine ZERO in front of the given number
• Than starting from the right hand side digit, multiply the number with 3 and write the number in the answer i.e. 4×3 = 12
• Than, come to the next digit (starting from right hand side only) and multiply the digit with 3 and add its right neighbour i.e. 3×3 + 4 = 12 + 1 (From previous step)
• Repeat Trebling each digit and adding its neighbour till last digit(as shown above) and you will get the answer.

So Rule is :

RULE – TREBLE MY EACH DIGIT IN TURN AND ADD MY RIGHT NEIGHBOUR

• MULTIPLICATION BY 25

Multiplication by 25 can also be done in two steps only. So these steps are:

• First, Put Two Zeroes at the right of the number ( or multiply by 100)
• Than, in second step, Divide it by 4; and you will get the answer.

Let’s see this with the help of example

Example:

34268 × 25=?

Isn’t this will be lengthy calculation if we will do it with the Traditional method. But here we will solve this with two simple steps. So the rule is :

RULE – MULTIPLY ME BY 100 AND DIVIDE ME BY 4

• MULTIPLICATION OF NUMBERS CLOSE TO 100, 1000,etc.

As we all know that multiplication with big numbers waste lot of our time while attempting the exam and specially when numbers are close to 100, 1000 etc i.e. big numbers. Here we will share the trick which helps you to save your time while solving these types of calculations.

Let’s understand this with the help of example:

Example:

97 × 93=? Take Base as 100(as these numbers are near to 100), and check the distance of the numbers from 100. Here difference is of -3 and -7. Now, take cross sum or difference of the numbers which shows distance of the numbers from 100. Here we can see, 97-7 = 90 or 93-3 is 90. (you can do either way, result will be same) and write 00 with the answer. (as Base is 100) In last step, we will do cross multiplication of the numbers that show the distance of the numbers from 100. i.e. -3×-7 = 21 and add this to the above step. So the answer will be 9021

• Note – You must consider the SIGNS of the number while applying this trick.

Let’s take one more example in which numbers are close to 1000

Example:

996 × 983 =? (We have written 3 Zeroes here as Base is 1000.)

With this we will finish this topic. Some of you may wonder what is the use of discussing all these tricks or how may these save our time. But friends, try to use this tricks while doing any type of questions and you fill the difference that how quick you have become to get the solutions.

Hope you have enjoyed learning. Please give your feedback in comment box.

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