NCERT Book Class 7 Maths Chapter 2 Fractions and Decimals

20 MATHEMATICS

Chapter 2
Fractions and
Decimals
2.1 MULTIPLICATION OF FRACTIONS
You know how to find the area of a rectangle. It is equal to length × breadth. If the length
and breadth of a rectangle are 7 cm and 4 cm respectively, then what will be its area? Its
area would be 7 × 4 = 28 cm2.
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What will be the area of the rectangle if its length and breadth are 7 cm and
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1 1 1 15 7 15
3 cm respectively? You will say it will be 7 × 3 = × cm2. The numbers
2 2 2 2 2 2
7
and are fractions. To calculate the area of the given rectangle, we need to know how to
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multiply fractions. We shall learn that now.

2.1.1 Multiplication of a Fraction by a Whole Number
1
Observe the pictures at the left (Fig 2.1). Each shaded part is
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part of a circle. How much will the two shaded parts represent together?
1 1 1
They will represent+ = 2× .
4 4 4
Fig 2.1
Combining the two shaded parts, we get Fig 2.2 . What part of a circle does the
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shaded part in Fig 2.2 represent? It represents part of a circle .
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Fig 2.2