Multiplication of the Algebraic Expressions
(i) Look at the following pattern of stars.Â
Pattern of Stars 
Total No. of Stars 
* * * * * * * * * * * * * * * * * * * * * 
3 Ã— 7 3  rows, 7 columns 
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
5 Ã— 6 5  rows, 6 columns 
m Ã—n m rows, n  columns Â 


(m + 2) Ã— (n + 1) (m + 2) rows (n + 1) columns Â 
To find the number of stars we have to multiply the expression for the number of rows by the expression for the number of columns.
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The above pattern of stars shows the rectangle shape. We can think of area of a rectangle. The area of a rectangle is l Ã— b, where l is the length and b is the breadth.
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If the length of the rectangle is increased by 3 units.
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Example :(l + 3) and breadth decreased by 8 units,
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Example : (b  8) then the area of the new rectangle will be (l + 3) (b  8)
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(iii) Consider an example of chalk box. What is the volume of chalk box?
Chalk box is rectangular in shape. Then the volume is given by
Length Ã— breadth Ã— height
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(iv) When we buy or sell things of same type we have to carry multiplication.
For example, if cost of one dozen of apples is Rs. x and Sita buys z dozens of apples for a picnic. Find the cost which she has to pay.
Price of Apples per dozen = Rs.x
For picnic apples needed = z dozens
Cost sita has to pay = Rs.Â (xz)
Suppose, the price per dozen was less by Rs. 4 and the apples needed were less by 6 dozens.
Price of aples per dozen = Rs (x  4)
Apples needed = (z 6) dozens
Then Sita has to pay = Rs. (x  4) Ã— (z  6)