Page 28 - Maths Skills - 7

26 Maths

Exercise 2.1

1. Add the following.

5 3 7 5 13 7 33 24 22
(i) + (ii) + (iii) + (iv) + +
11 11 17 17 51 51 125 125 125
2. Subtract the first fraction from the second.

1 7 31 41 35 41 21 41
(i) , (ii) , (iii) , (iv) ,
15 15 71 71 37 37 91 91
3. Find the sum.

1 5 2 7 3 1 1 6
(i) + (ii) + (iii) + (iv) 2 +
17 34 5 25 71 142 3 7
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(v) 5 + 7 1 (vi) 1 + 6 1 (vii) 3 + 3 (viii) 5 + + 5 1
2 3 9 3 5 9 2 2
4. Find the difference.
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(i) 5 – 7 (ii) 15 − 11 (iii) 13 – 1 (vi) 2 – 13
11 22 73 146 34 51 5 15

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5. The cost of a notebook is ` 25 and that of a pen is ` 12 . Which costs more and by how much?
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6. A shopkeeper sold 2 kg of wheat bags from a 31 kg sack. Calculate how many kg of wheat is left in
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the sack?
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7. Deepa bought 4 kg of mangoes and 7 kg of apples. What is the total weight of fruits purchased by
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her? On her way back to home she gave 1 kg of total fruits to an orphanage. How much is left with
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her now?

MULTIPLICATION OF FRACTIONS
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To understand the multiplication of fractions, let us take an example, × or of 1
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Here, we find that when we multiply two fractions,
(i) The numerator is multiplied by the numerator.
(ii) The denominator is multiplied by the denominator.
6 2 62× 12 3 2 32× 6
For example; (i) × = = (ii) × = =
10 11 10 11 110× 7 13 713× 91
While multiplying fractions we may have two possibilities.

(i) Multiplying a Fraction by a Whole Number
● We multiply a proper or an improper fraction by a whole number by multiplying the numerator of the
fraction by the whole number and keep the denominator same.
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For example, let us multiply and 4.
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