Exercise 1.1

Exercise 1.1

1. Write the decimal numbers for the following pictorial representation of numbers.

Answer:

(i) 12.2

(ii) 21.3

2. Express the following in cm using decimals.

(i) 5 mm

(ii) 9 mm

(iii) 42 mm

(iv) 8 cm 9 mm

(v) 375 mm

i) 5 mm = 5/10 cm = 0.5 cm

ii) 9 mm = 9/10 cm = 0.9 cm

iii) 42 mm = 42/10 cm = 4.2 cm

iv) 8 cm 9 mm = 8 +   42/10 cm  = 8.9 cm

v) 375 mm = 375/10 cm = 37.5 cm

3. Express the following in metres using decimals.

(i) 16 cm

(ii) 7 cm

(iii) 43 cm

(iv) 6 m 6 cm

(v) 2 m 54 cm

i) 16 cm = 16 /100 m = 0.16 m

ii) 7 cm = 7/100 m = 0. 07m

iii) 43 cm = 43 /100 m = 0.43 m

iv) 6 m 6 cm = 6 +   6 /100 m = 6.06 m

v) 2 m 54 cm = 2 +   54/100 m = 2.54 m

4. Expand the following decimal numbers.

(i) 37.3

(ii) 658.37

(iii) 237.6

(iv) 5678.358

i) 37.3

Expanded form of

37.3 = 30 + 7 +  (3/10)

ii) 658.37

Expanded form of

65837 = 600 + 50 + 8 +  3/10 + 7/100

iii) 237.6

Expanded form of

2376= 200 + 30 + 7+  6/10

iv) 5678.358

Expanded form of

5678358 = 5000 – 600 + 70 + 8 + 3/10 + 5/100 + 8 /1000

5. Express the following decimal numbers in place value grid and write the place value of the underlined digit.

(i) 53.61

(ii) 263.271

(iii) 17.39

(iv) 9.657

(v) 4972.068

(i) 53.61

Place value grid

53.6 1

The place value of 6 in 53.61 is Tenth.

(ii) 263.2 71

Place value grid

263.2 71

The place value of 2 in 263.271 is Tenth = 2/10

(iii) 17.39

Place value grid

17.39

The place value of 9 in 17.39 is Hundredth = 9/100

(iv) 9.657 

Place value grid

9.657

The place value of 5 in 9.657 is Hundredth = 5/100

(v) 4972.068

Place value grid

4972.068

The place value of 8 in 4972.068 is Thousandth = 8/1000

Objective type questions

6. The place value of 3 in 85.073 is _______

(i) tenths

(ii) hundredths

(iii) thousands

 (iv) thousandths

Answer: (iv) thousandths

7. To convert grams into kilograms, we have to divide it by

(i) 10000

(ii) 1000

(iii) 100

(iv) 10

Answer: (ii) 1000

8. The decimal representation of 30 kg and 43 g is ____ kg.

(i) 30.43

(ii) 30.430

(iii) 30.043

(iv) 30.0043

Answer: (iii) 30.043

9. A cricket pitch is about 264 cm wide. It is equal to ____ m.

(i) 26.4

(ii) 2.64

(iii) 0.264

(iv) 0.0264

Answer: (ii) 2.64

ANSWERS:

Exercise 1.1

1. (i) 12.2 (ii) 21.3

2. (i) 0.5 cm (ii) 0.9 cm (iii) 4.2 cm (iv) 8.9 cm (v) 37.5 cm

3. (i) 0.16 m (ii) 0.07 m (iii) 0.43 m (iv) 6.06 m (v) 2.54 m

4. (i) 30 + 7 + 3/10 (ii) 600 + 50 + 8 + 3/10 + 7/100 (iii) 200+30+7+  6/10 (iv) 5000 + 600 + 70 + 8 + 3/10 + 5/100 + 8/1000

5. 

 Objective type questions

6. (iv) thousandths

7. (ii) 1000

8. (iii) 30.043

9. (ii) 2.64