Question

Tính bằng cách thuận tiện:

a) 167 x 56 + 44 x 167 b) 178 x 67 + 178 x 81 – 48 x 178 c) 132 : 4 + 212 : 4 + 56 : 4 d) (1 + 2 + 3 + … + 99) x (132 x 3 – 99 x 4)

Answer 1

a) 167 x 56 + 44 x 167

= 167 x ( 56 + 44)

= 167 x 100 = 16700

b) 178 x 67 + 178 x 81 – 48 x 178

= 178 x ( 67 + 81 - 48 )

= 178 x 100 = 17800

c) 132 : 4 + 212 : 4 + 56 : 4

= ( 132 + 212 + 56 ) : 4

= 400 : 4 = 100

d) (1 + 2 + 3 + … + 99) x (132 x 3 – 99 x 4)

= ( 1 + 2 + 3 + ... + 99) x [( 33 x 4 ) x 3 - ( 33 x 3) x 4]

= ( 1 + 2 + 3 +....+ 99) x [ 33 x ( 4 x 3 ) - 33 x ( 3 x 4)]

= ( 1 + 2 + 3 + ... + 99) x ( 33 x 12 - 33 x 12)

= ( 1 + 2 + 3 + ... + 99) x 0

=0