1.Find:

(i) 0.2 × 6

Solution:

First, we multiply 2 × 6 = 12

Now, put the decimal point from 1 digit right because we have decimal point from one digit in 0.2

Hence, 0.2 × 6 = 1.2

(ii) 8 × 4.6

Solution:

First, we multiply 8 × 46 = 368

Now, put the decimal point from 1 digit right because we have decimal point from one digit in 4.6

Hence, 8 × 4.6 = 36.8

(iii) 2.71 × 5

Solution:

First, we multiply 271 × 5 = 1355

Now, put the decimal point from 2 digits right because we have decimal point from two digit in 2.71

Hence, 2.71 × 5 = 13.55

(iv) 20.1 × 4

Solution:

First, we multiply 201 × 4 = 804

Now, put the decimal point from 1 digit right because we have decimal point from one digit in 20.1

Hence, 20.1 × 4 = 80.4

(v) 0.05 × 7

Solution:

First, we multiply 5 × 7 = 35

Now, put the decimal point from 2 digits right because we have decimal point from two-digit in 0.05

Hence, 0.05 × 7 = 0.35

(vi) 211.02 × 4

Solution:

First, we multiply 21102 × 4 = 84408

Now, put the decimal point from 2 digits right because we have decimal point from two-digit in 211.02

Hence, 211.02 × 4 = 844.08

(vii) 2 × 0.86

Solution:

First, we multiply 2 × 86 = 172

Now, put the decimal point from 2 digits right because we have decimal point from two-digit in 0.86

Hence, 2 × 0.86 = 1.72

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

Solution:

Given,

Length = 5.7 cm

breadth = 3 cm

Now,

Area of rectangle = length × breadth

= 5.7 cm × 3 cm

= 17.1 cm²

Hence, requird area is 17.1 cm²

3. Find:

(i) 1.3 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

1.3 × 10 = 13

(ii) 36.8 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

36.8 × 10 = 368

(iii) 153.7 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

153.7 × 10 = 1537

(iv) 168.07 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

168.07 × 10 = 1680.7

(v) 31.1 × 100

Solution:

When we multiply a decimal by 100, the point of decimal is shifted to the right by two places.

Thus,

31.1 × 100 = 3110.0

= 3110

(vi) 156.1 × 100

Solution:

When we multiply a decimal by 100, the point of decimal is shifted to the right by two places.

Thus,

156.1 × 100 = 15610.0

= 15610

(vii) 3.62 × 100

Solution:

When we multiply a decimal by 100, the point of decimal is shifted to the right by two places.

Thus,

3.62 × 100 = 362

(viii) 43.07 × 100

Solution:

When we multiply a decimal by 100, the point of decimal is shifted to the right by two places.

Thus,

43.07 × 100 = 362

(ix) 0.5 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

0.5 × 10 = 5

(x) 0.08 × 10

Solution:

When we multiply a decimal by 10, the point of decimal is shifted to the right by one place.

Thus,

0.08 × 10 = 0.8

(xi) 0.9 × 100

Solution:

When we multiply a decimal by 100, the point of decimal is shifted to the right by two places.

Thus,

0.9 × 100 = 90

(xii) 0.03 × 1000

Solution:

When we multiply a decimal by 1000, the point of decimal is shifted to the right by three places.

Thus,

0.03 × 1000 = 30

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:

Given,

Distance covered by a two-wheeler in 1-litre petrol = 55.3 Km

Now,

Distance covered by a two-wheeler in 10-litre petrol = 10 × 55.3

= 553 km

5. Find:

(i) 2.5 × 0.3

Solution:

(ii) 0.1 × 51.7

Solution:

(iii) 0.2 × 316.8

Solution:

(iv) 1.3 × 3.1

Solution:

(v) 0.5 × 0.05

Solution:

(vi) 11.2 × 0.15

Solution:

(vii) 1.07 × 0.02

Solution:

(viii) 10.05 × 1.05

Solution:

(ix) 101.01 × 0.01

Solution:

(x) 100.01 × 1.1

Solution: