# Exercise 2.4

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**1.Find:**

**Solution:**

(1)0.2×6=

(2)8×4.6=

(3)2.71×5=

(4)20.1×4=

(5)0.05×7=

(6)211.02×4=

(7)2×0.86=

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**2.Find the area of rectangle whose length is 5.7 cm and breadth is 3 cm**

**Solution:**

We use the formula for area of the rectangle and concepts of decimals to solve the question.

Given:

Length of rectangle =

Breadth of rectangle =

∴ Area of rectangle = Length × Breadth

= 5.7 × 3 =

**Thus, the area of rectangle is 17.1 cm2.**

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**1.Find:**

**Solution:**

### a

We use the concepts of decimal multiplication to solve the problem given.

(i)1.3 × 10 =

(ii) 36.8 × 10 =

(iii)153.7× 10 =

(iv)168.07 × 10 =

### b

(v) 31.1 × 100 =

(vi)156.1 × 100 =

(vii) 3.62 × 100 =

(viii) 43.07 × 100 =

### c

(ix) 0.5 × 10 =

(x) 0.08 × 10 =

(xi) 0.9 × 100 =

(xii) 0.03 × 1000 =

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**4.A two-wheeler covers a distance of 55.3 km in one litre of petrol. How much distance will it cover in 10 litres of petrol?**

**Solution:**

We use the basic concepts of multiplication and decimals to solve the question.

By using Unitary Method, we can simply multiply 55.3 by 10 to get the answer.

Distance covered by two-wheeler in 1 litre of petrol =

Distance covered using 10 liters of petrol = 55.3 × 10 =

**Therefore, it will cover a distance of 553 km in 10 liters of petrol.**

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**5.Find:**

**Solution:**

### a

We will use the concepts of decimals and fractions to solve the given questions.

(i) 2.5 × 0.3

= 25/10 × 3/10

= 25 × 3/100

= 75/100

=

(ii) 0.1 × 51.7

= 1/10 × 517/10

= 1 × 517/100

= 517/100

=

(iii) 0.2 × 316.8

= 2/10 × 3168/10

= 2 × 3168/100

= 6336/100

=

(iv) 1.3 × 3.1

= 13/10 × 31/10

= 13 × 31/100

= 403/100 =

(v) 0.5 × 0.05

= 5/10 × 5/100

= 5 × 5/1000

= 25/1000

=

### b

(vi) 11.2 × 0.15

= 112/10 × 15/100

= 112 × 15/1000

= 1680/1000

=

(vii) 1.07 × 0.02

= 107/100 × 2/100

= 107 × 2/10000

= 214/10000

=

(viii) 10.05 × 1.05

= 1005/100 × 105/100

= 1005 × 105/10000

= 105525/10000

=

(ix) 101.01 × 0.01

= 10101/100 × 1/100

= 10101 × 1/10000

= 10101/10000

=

(x) 100.01 × 1.1

= 10001/100 × 11/10

= 10001 × 11/1000

= 110011/1000

=