Category : 2nd Class
LEARNING OBJECTIVES
This lesson will help you to:—
QUICK CONCEPT REVIEW
MULTIPLICATION
What is a Group?
Let us understand with the help of examples.
There are 5 pencils in this box. We can say this is group of 5 pencils.
Now consider two boxes of pencils.
These are 2 groups of 5 pencils each. Equal groups
Look at these three groups of birds.
There is an equal number of birds in each group i.e., 3.
To find the total number of birds, the same number is added again and again. This repeated addition is called multiplication.
Amazing Facts
Any two number multiplied in any order or sequence gives the same answer.
For Example: \[10\times 2=20\]and
\[2\times 10=20\]
PROPERTIES OF MULTIPLICATION
\[4\times 2=8\]
In this example, the number 8 is the product.
\[0\times 1='0'1\times 0='0'\]
Real Life Examples
If you want to buy 10 dozens of banana then you can calculate the number of banana as well as its price by the method of multiplication.
For Example.
1 dozen = 12 bananas
10 dozen = \[12\times 10=120\]bananas
If cost of 1 dozen banana is Rs. 10
Then const of 10 banana can be calculated as:
\[10\times Rs.10=Rs.100\]
Let us discuss some examples:
1. Look at the 3 lots of 5 pencils
Each lot has 5 pencils,
Therefore, 5 + 5 + 5 = 15.
or '3 x 5 = 15
or "3 multiplied by 5 is 15'.
or '3 times 5 is 15.'
2. How many legs will 5 horses have?
Each horse has 4 legs. So, 5 horses will have
\[\text{4}+\text{4}+\text{4}+\text{4}+\text{4}=\text{ 2}0\text{ Legs}.\]
In this 4 is repeatedly added 5 times.
or, \[\text{4 }\times \text{ 5 }=\text{ 2}0\]
Do you know?
Now, you must be thinking that how to do big repeated additions. It will be very difficult.
For that, you can use multiplication tables which are made for two times, three time____ upto ten times.
Let us write these multiplication facts in a table.
Following are multiplication tables of 3 and 5.
Multiplications Table of 3 

\[1\times 3=3\] 
\[6\times 3=18\] 
\[2\times 3=6\] 
\[7\times 3=21\] 
\[3\times 3=9\] 
\[8\times 3=24\] 
\[4\times 3=12\] 
\[9\times 3=27\] 
\[5\times 3=15\] 
\[10\times 3=30\] 
Multiplications Table of 5 

\[1\times 5=5\] 
\[6\times 5=30\] 
\[2\times 5=10\] 
\[7\times 5=35\] 
\[3\times 5=15\] 
\[8\times 5=40\] 
\[4\times 5=20\] 
\[9\times 5=45\] 
\[5\times 5=25\] 
\[10\times 5=50\] 
MULTIPLICATION OF COLUMN FORM
\[3\times 4=12\] \[2\times 6=12\]

T 
O 


T 
O 


3 



2 
\[\times \] 

4 

\[\times \] 

6 
= 
1 
2 

= 
1 
2 
Let us take an example
\[\text{12}\times \text{3}=\text{36}\]

T 
O 

1 
2 
\[\times \] 

3 
= 
3 
6 
First multiply 2 ones of 12 with 3, \[\text{2}\times \text{3}=\text{6}\].
Then multiply 1 tens of 12 with 3, \[\text{1}\times \text{3}=\text{3}\]
hence, \[\text{12 }\times \text{ 3 }=\text{ 36}\].
Let us now consider some examples of multiplication involving carry over.
For example:
\[\text{18}\times \text{5}=\text{9}0\]

T 
O 

\[^{4}1\] 
8 
\[\times \] 

5 
= 
9 
0 
Here, 4 is carried over from ones place and this is added in the product of \[\text{1}\times \text{5}=\text{5}\] and \[\text{5}+\text{4}=\text{9}\]
hence, \[\text{18}\times \text{5}=\text{9}0\].
SOME IMPORTANT CONCEPT
Which can also be written as\[~\text{2}\times \text{5}=\text{1}0\]
or\[~\text{5}\times \text{2}=\text{1}0\].
Examples:
\[\text{l}\times \text{24}=\text{2}\times \text{12 }=\text{3}\times \text{8}=\text{4}\times \text{6}\]
\[\text{l}\times \text{18 }=\text{2}\times \text{9}=\text{3}\times \text{6}=\text{9}\times \text{2}\]
Example: \[~\text{4}\times \text{1}0=\text{4}0\].
Historical preview
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