SChand New Learning Composite Mathematics Class 6 Chapter 2 Whole Numbers Exercise 2B

 Exercise 2B

Question 1

(a) 8396 x 1 = 8396

(b) 64937 x 0 = 0

(c) 45 x 7 = 7 x 45

(d) (7 x 4) x 3= 7 x (4 x 3)

(e) 194 x 23 = 194 x (20 + 3)

(f) 89 x 302 = 89 x 300 + 89 x 2

(g) 57 x 29 = 57 x 20 + 57 x 5 + 57 x 4

(h) 12(8 – 5) = (12 x 8) – (12 x 5)

Question 2

(a) Identity property

(b) Property of zero

(c) Commutative Property

(d) Commutative Property

(e) Distributive Over Addition

(f) Associative Property.

Question 3

(a) 50 x 27 x 2

= (50 x 2) x 27 [Associative Property]

= 100 x 27

= 2700

(b ) 4 x (9 x 25)

= 4 x 225

= 900

(c) 25 x 39 x 8

= (25 x 8) x 39 [Associative Property]

= 200 x 39

= 7800

(d) 625 x 20 x 8 x 50

= (625 x 20) x (8 x 50) [Group the factor to make calculation easy]

= 12500  x 400

= 50,00,000

(e) 16 x 250 x 125 x 2

= (16 x 250) x (125 x 2) [Group the factor to make calculation easy]

= 4000 x 250

= 1,0,00,000

Question 4

(a) 79328 x 93 + 7 x 79328

= 79328 x (93 +7) [ Distributive Property over addition]

= 79328 x 100

= 7932800

(b) 8057 x 59 + 8057 x 25 + 8057 x 16

= 8057 x (59 + 25 + 16) [Distributive Property over addition]

= 8057 x 100

= 805700

Question 5

(a) 9 x 15

= (10 – 1) x 15

= (10 x 15) – (1 x 15)

= 150 – 15

= 135

(b) 82 x 103

= 82 x (100 + 3)

= (82 x 100) + (82 x 3)

= 8200 + 246

= 8446

(c) 7 x 124

= 7 x (100 + 24)

= (7 x 100) + (7 x 24)

= 700 + 168

= 868

(d) 3807 x 8

= (3800 + 7) x 8

= (3800 x 8) + (7 x 8)

= 30400 + 56

= 30456

(e) 258 x 1008

= 258 x (1000 + 8)

= (258 x 1000) + (258 x 8)

= 258000 + 2064

= 260064

(f) 869 x 10005

= 869 x (10000 + 5)

= (869 x 10000) + (869 x 5)

= 8690000 + 4345

= 8694345