**Whole Numbers**

**Exercise 2.2**

Examples for Practice

1). Find the sum by suitable rearrangement.

a). 837 + 208 + 363

837 + 208 + 363 = (837 + 363) + 208

= 1200 + 208

= 1408

Ans: 837 + 208 + 363 = 1,408

b). 1962 + 453 + 1538 + 647

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

= 3500 + (453 + 647)

= 3500 + 1100

= 4600

Ans: 1962 + 453 + 1538 + 647 = 4,600

2). Find the product by suitable rearrangement.

a). 2 X 1768 X 50

2 X 1768 X 50 = (2 X 50) X 1768

= 100 X 1768

= 176800

Ans: 2 X 1768 X 50 = 1,76,800

b). 4 X 166 X 25

4 X 166 X 25 = (4 X 25) X 166

= 100 X 166

= 16600

Ans : 4 X 166 X 25 = 16,600

c). 8 X 291 X 125

8 X 291 X 125 = (8 X 125) X 291

= 1000 X 291

= 291000

Ans: 8 X 291 X 125 = 2,91,000

d). 625 X 279 X 16

625 X 279 X 16 = (625 X 16) X 279

= 10000 X 279

= 2790000

Ans: 625 X 279 X 16 = 27,90,000

e). 285 X 5 X 60

285 X 5 X 60 = 285 X (5 X 60)

= 285 X 300

= 85500

285 X 5 X 60 = 85,500

f). 125 X 40 X 8 X 25

__Method I__

125 X 40 X 8 X 25 = (125 X 40) X (8 X 25)

= 5000 X 200

= 1000000

Ans: 125 X 40 X 8 X 25 = 10,00,000

__Method II__

125 X 40 X 8 X 25 = (125 X 8) X (40 X 25)

= 1000 X 1000

= 1000000

Ans: 125 X 40 X 8 X 25 = 10,00,000

3). Find the value of the following:

a). 297 X 17 + 297 X 3

297 X 17 + 297 X 3 = __297__ X 17 + __297__ X 3

= 297 ( 17 + 3)

= 297 X 20

= 5940

Ans: 297 X 17 + 297 X 3 = 5,940

b). 54279 X 92 + 8 X 54279

54279 X 92 + 8 X 54279 = __54279__ X 92 + 8 X __54279__

= 54279 ( 92 + 8)

= 54279 X 100

= 5427900

Ans: 54279 X 92 + 8 X 54279 = 54,27,900

c). 81265 X 169 – 81265 X 69

81265 X 169 – 81265 X 69 = __81265__ X 169 – 81265 X 69

= 81265 X (169 – 69)

= 81265 X 100

= 8126500

Ans: 81265 X 169 – 81265 X 69 = 81,26,500

d). 3845 X 5 X 782 + 769 X 25 X 218

3845 X 5 X 782 + 769 X 25 X 218

= (3845 X 5) X 782 + (769 X 25) X 218

= 19225 X 782 + 19225 X 218

= 19225 X (782 + 218)

= 19225 X 1000

= 19225000

Ans: 3845 X 5 X 782 + 769 X 25 X 218 = 1,92,25,000

4). Find the product using suitable properties.

a). 738 X 103

738 X 103 = 738 X (100 + 3)

= 738 X 100 + 738 X 3

= 73800 + 2214

= 76014

Ans: 738 X 103 = 76,014

b). 854 X 102

854 X 102 = 854 X (100 + 2)

= 854 X 100 + 854 X 2

= 85400 + 1708

= 87108

Ans: 854 X 102 = 87,108

c). 258 X 1008

258 X 1008 = 258 X (1000 + 8)

= 258 X 1000 + 258 X 8

= 258000 + 2064

= 260064

Ans: 258 X 1008 =2,60,064

d). 1005 X 168

1005 X 168 = (1000 + 5) X 168

= 1000 X 168 + 5 X 168

= 168000 + 840

= 168840

Ans: 1005 X 168 =168840

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 44 per litre, how much did he spend in all on petrol?

Petrol filled in the tank on Monday = 40 litres

Petrol filled next day = 50 litres

Cost of the petrol = Rs 44 per litre

Total spend on the petrol =?

Total petrol filled in the car= 40 + 50

= 90 litres

Cost of the total petrol = 90 X 44

= Rs 3960

Ans: Total spend on the petrol = Rs 3,960.

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 rupees 45 per litre, how much money is due to the vendor per day?

Milk supplied in the morning = 32 litres

Milk supplied in the evening = 68 litres

Cost of the milk = Rs 45 per litre

Total milk supplied is = 32 + 68

= 100

Total money spend on the milk = 100 X 45

= 4500

Ans: Total money spend on the milk= Rs 4,500.

7). Match the following:

i). 425 X 136 = 425 X (6+30+100) a). commutative under

multiplication

ii). 2 X 49 X 50 = 2 X 50X 49 b). commutative under

addition

iii). 80 + 2005 + 20 = 80 + 20 + 2005 c). Distributivity of

multiplication

Answers:

i). 425 X 136 = 425 X (6+30+100 – Distributivity of multiplication

ii). 2 X 49 X 50 = 2 X 50X 49 – commutative under multiplication

iii). 80 + 2005 + 20 = 80 + 20 + 2005 – commutative under addition.

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