**Trick 1 :**
Multiply any two numbers from 11 to 20 in your
head.
Take 15 × 13 for example… Place the larger no.
first in your mind and then do something like this Take the larger
no on the top and the second digit of the smaller no. in the
bottom.
15
3
The rest is quite simple. Add 15+3 = 18 . Then
multiply 18 × 10 = 180 …
Now multiply the second digit of both the no.s
(ie; 5 × 3 = 15) Now add 180 + 15.

Here is
the answer 180 + 15 = 195 . Think over it.
This is a simple trick. It will help you a lot.

Trick 2 **:**
Multiply any two digit number with 11.

This trick is much simpler than the previous one
and it is more useful too. Let the number be 27 . Therefore 27 ×
11

Divide the number as 2 _ 7

Add 2+ 7 = 9

Thus the answer is 2 9 7

Wasn't this one simple. But there is one
complication. If you take a number like 57 Thus _57 x 11

Divide the number as 5 _ 7

Add 5 + 7 = 12

Now add 1 to 5 and place 2 in the middle so the
answer is 5+1_2 _7 = _627

Thus the answer is 627.

Trick 3 **:**
Multiply any number from 1 to 10 by 9 To multiply by 9, try
this:

(1) Spread your two hands out and place them on a
desk or table in front of you.

(2) To multiply by 3, fold down the 3rd finger
from the left. To multiply by 4, it would be the 4th finger and so
on.

(3) the answer is 27 … READ it from the two fingers on the left of the
folded down finger and the 7 fingers on the right of it. This one
was really cool wasn't it.

**Trick 4****:** Square a two digit number ending in five.
This one is as easy as the previous ones but you have to pay a
little more attention to this one . Read carefully :Let the number
be 35

35 × 35

Multiply the last digits of both the numbers ;
thus ___ 5 × 5 = 25

now add 1 to 3 thus 3 + 1 = 4

multiply 4 × 3 = 12

thus answer 1225

You will have to think over this one carefully.As 5 has to come in
the end so the last two digits o the answer will be 25 . Add 1 to
the first digit and multiply it by the original first digit . Now
this answer forms the digits before the 25. Thus we get an
answer.

**Trick 5**
**:** Square any two digit
number.

Suppose the number is 47 . Look for the nearest multiple of 10 .
ie; in this case 50. We will reach 50 if we add 3 to 47. So
multiply (47+3) x (47-3) = 50 × 44 = 2200 This is the 1st interim
answer.

We had added 3 to reach the nearest multiple of 10 that is 50 thus
3x 3 = 9 This is the second interim answer.

The final answer is 2200 + 9 = 2209 … Practice
This one on paper first.

Trick 6 **:**
Multiply any number by 11 .

Trick number 2 tells you how to multiply a two digit number by 11
but what if you have a number like 12345678. Well that is very easy
if you our trick as given below. Read it carefully.

Let the number be 12345678 __ thus 12345678 × 11

Write down the number as 012345678 ( Add a 0 in the
beginning)

Now starting from the units digit write down the
numbers after adding the number to the right, so the answer will be 135802458

This one is simple if you think over it properly all you got to do
is to add the number on the right . If you are getting a carry over
then add that

to the number on the left. So I will tell you how I got the answer
. Read carefully. The number was 12345678 ___ I put a 0 before the
number ____ so the new number 012345678 Now I wrote ___
012345678

Then for the answer

8 + 0 = 8

7 + 8 = 15 (1 gets carry carried over)

6+1+7 = 14 ( 1 gets carried over)

5 + 1 + 6 = 12 ( 1 gets carried over)

4 + 1 + 5 = 10 ( 1 gets carried over)

3 + 1 + 4 = 8

2 + 3 = 5

1 + 2 = 3

0 + 1 = 1

Thus the answer = 135802458

**Trick 7** **:** 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 34×40

The way I do it is 34×10=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.

3×3=9 which is the SECOND interim answer.

Add the two interim answers to get the final
answer.

**Answer:** 1360 + 9 =
1369

With practice this can easily be done
in your head.

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