Question

Tính nhanh

a) 2 . 31 . 12 + 4 . 6 . 42 + 8 . 27 . 3

b) 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41

Answer 1

a) A = 2.31.12 + 4.6.42 + 8.27.3

= 24.31 + 24.42 + 24.27

= 24.(31 + 42 + 27)

= 24.100 = 2400

b) B = 36.28 + 36.82 + 64.69 + 64.41

= 36.(28 + 82) + 64.(69 + 41)

= 36.110 + 64.110

= 110.(36 + 64)

= 110.100 

= 11000

Answer 2

a,  2 . 31 . 12 + 4 . 6 . 42 + 8 . 27 . 3 

= 24 . 31 + 24 . 42 + 24 . 27

= 24 . ( 31 + 42 + 27 )

=  24 . 100 = 2400

b, 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41

= 36 . ( 28 + 82 ) + 64 . ( 69 + 41 ) 

= 36 . 110 +  64 . 110 

= 110 . ( 36 + 64 ) 

= 110 . 100 = 11000