USING SUITABLE REARRANGEMENT AND FIND THE PRODUCT

Determine the product using suitable rearrangements :

Problem 1 :

8 x 125 x 40 x 25

Solution :

= 8 x 125 x 40 x 25

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

= 1000 x 1000

= 1000000

So, the answer is 1000000.

Problem 2 :

250 x 60 x 50 x 8

Solution :

= 250 x 60 x 50 x 8

= 250 x 60 x 50 x 2 x 4

= (250 x 4) x (50 x 2) x 60

 = 1000 x 100 x 60

= 10000 x 60

= 600000

Problem 3 :

37256 x 25 x 9 x 40

Solution :

= 37256 x 25 x 9 x 40

= 37256 x 25 x 9 x 4 x 10

= 37256 x (25 x 4) x 10 x 9

= 37256 x 100 x 10 x 9

= 335304 x 1000

= 335304000

Problem 4 :

2 x 1497 x 50

Solution :

= 2 x 1497 x 50

= (2 x 50) x 1497

= 100 x 1497

= 149700

Problem 5 :

4 x 358 x 25

Solution :

= 4 x 358 x 25

= (4 x 25) x 358

= 100 x 358

= 35800

Problem 6 :

625 x 20 x 8 x 50

Solution :

= 625 x 20 x 8 x 50

= 625 x 2 x 10 x 8 x 50

= 625 x (8 x 2) x (10 x 50) 

= 625 x 16 x 500

= 10000 x 500

= 5000000

Problem 7 :

25 x 8358 x 4

Solution :

= 25 x 8358 x 4

= (25 x 4) x 8358

= 100 x 8358

= 835800

Problem 8 :

625 x 3759 x 8

Solution :

= 625 x 3759 x 8

= 125 x 5 x 3759 x 8

= (125 x 8) x (5 x 3759)

= 1000 x 18795

= 18795000

Problem 9 :

69 x 78 + 22 x 69

Solution :

= 69 x 78 + 22 x 69

= 69 x (78 + 22)

= 69 x 100

= 6900

Problem 10 :

126 x 55 + 126 x 45

Solution :

= 126 x 55 + 126 x 45

= 126 x (55 + 45)

= 126 x 100

= 12600

Problem 11 :

50 chairs and 30 black boards were purchased for a school. If each chair costs $165 and the blackboard costs $445, find the total amount of the bill.

Solution :

Cost of one chair = $165

Number of chairs purchased = 50

Cost of each blackboard = $445

Number of blackboards purchased = 30

Total amount = 165 x 50 + 445 x 30

= 165 x 5 x 10 + 445 x 3 x 10

= 825 x 10 + 1335 x 10

= 10 x (825 + 1335)

= 10 x 2160

= 21600

So, the bill amount is 21600.