Whole Numbers-Solutions Ex-2.2

CBSE Class –VI Mathematics
NCERT Solutions
Chapter 2 Whole Numbers (Ex. 2.2)

Question 1. Find the sum by suitable rearrangement:

(a) 837 + 208 + 363

(b) 1962 + 453 + 1538 + 647

Answer: (a) 837 + 208 + 363

= (837 + 363) + 208

= 1200 + 208

= 1408

(b) 1962 + 453 + 1538 + 647

= (1962 + 1538) + (453 + 647)

= 3500 + 1100

= 4600

Question 2. Find the product by suitable arrangement:

(a) 2 x 1768 x 50

(b) 4 x 166 x 25

(d) 625 x 279 x 16

(e) 285 x 5 x 60

(f) 125 x 40 x 8 x 25

Answer: (a) 2 x 1768 x 50

= (2 x 50) x 1768

= 100 x 1768

= 176800

(b) 4 x 166 x 25

= (4 x 25) x 166

= 100 x 166

= 16600

= (8 x 125) x 291

= 1000 x 291

= 291000

(d) 625 x 279 x 16

= (625 x 16) x 279

= 10000 x 279

= 2790000

(e) 285 x 5 x 60

= 285 x (5 x 60)

= 285 x 300

= 85500

(f) 125 x 40 x 8 x 25

= (125 x 8) x (40 x 25)

= 1000 x 1000

= 1000000

Question 3. Find the value of the following:

(a) 297 x 17 + 297 x 3

(b) 54279 x 92 + 8 x 54279

(d) 3845 x 5 x 782 + 769 x 25 x 218

Answer: (a) 297 x 17 + 297 x 3

= 297 x (17 + 3)

= 297 x 20

= 5940

(b) 54279 x 92 + 8 x 54279

= 54279 x (92 + 8)

= 54279 x 100

= 5427900

= 81265 x (169 – 69)

= 81265 x 100

= 8126500

(d) 3845 x 5 x 782 + 769 x 25 x 218

= 3845 x 5 x 782 + 769 x 5 x 5 x 218

= 3845 x 5 x 782 + 3845 x 5 x 218

= 3845 x 5 x (782 + 218)

= 3845 x 5 x 1000

= 19225000

Question 4. Find the product using suitable properties:

(a) 738 x 103

(b) 854 x 102

(d) 1005 x 168

Answer: (a) 738 x 103

= 738 x (100 + 3)

= 738 x 100 + 738 x 3

= 73800 + 2214

= 76014

(b) 854 x 102

= 854 x (100 + 2)

= 854 x 100 + 854 x 2

= 85400 + 1708

= 87108

= 258 x (1000 + 8)

= 258 x 1000 + 258 x 8

= 258000 + 2064

= 260064

(d) 1005 x 168

= (1000 + 5) x 168

= 1000 x 168 + 5 x 168

= 168000 + 840

= 168840

Question 5. A taxi-driver, filled his car petrol tank with 40 litres of petrol on Monday. The next day, he filled the tank with 50 litres of petrol. If the petrol costs Rs.44 per litre, how much did he spend in all on petrol?

Answer: Quantity of Petrol filled on Monday = 40 litres

Quantity of Petrol filled on next day = 50 litres

Total Quantity of petrol filled = 90 litres

Now, Cost of 1 litre petrol = Rs.44

Cost of 90 litres of petrol = 44 x 90

= 44 x (100 – 10)

= 44 x 100 – 44 x 10

= 4400 – 440

= Rs.3960

Therefore, he spent Rs.3960 on petrol.

Question 6. A vendor supplies 32 litres of milk to a hotel in the morning and 68 litres of milk in the evening. If the milk costs Rs.15 per litre, how much money is due to the vendor per day?

Answer: Quantity of milk supplied in the morning = 32 litres

Quantity of milk supplied in the evening = 68 litres

Total supply = 32 + 68 = 100 litres

Now Cost of 1 litre milk = Rs.15

Cost of 100 litres milk = 15 x 100 = Rs.1500

Therefore, Rs.1500 is due to the vendor per day.

Question 7. Match the following:

(i)425 x 136 = 425 x (6 + 30 + 100) (a) Commutativity under multiplication

(ii) 2 x 49 x 50 = 2 x 50 x 49 (b) Commutativity under addition

(iii) 80 + 2005 + 20 = 80 + 20 + 2005 (c) Distributivity of multiplication over addition

Answer: (i) 425 x 136 = 425 x (6 + 30 + 100) (c) Distributivity of multiplication over addition

(ii) 2 x 49 x 50 = 2 x 50 x 49 (a) Commutativity under multiplication

(iii) 80 + 2005 + 20 = 80 + 20 + 2005 (b) Commutativity under addition.