Question

tính nhanh

a) 60-26.75-13.25

b)45.78+38.42-25.78-18.42

c)72.9*99+72+0.9

d)3.4*4+1.7*8+3.4*2

Answer 1

a 60 - 26,75 - 13,25

= 60 - ( 26,75 + 13,25 )

= 60 - 40

= 20

b ) 45,78 + 38,42 - 25,78 - 18,42

= ( 45,78 - 25,78 ) + ( 38,42 - 18,42 )

= 20 + 20

= 40

Answer 2

a=20

b=40

c=7290

d=26

Answer 3

a,60-26.75-13.25

=60-26.3.25-13.25

=60-78.25-13.25

=60-25.(78+13)

=60-2275

=-2215

Answer 4

b,45.78+38.42-25.78-18.42

=(45.78-25.78)+(38.42-18.42)

=78.(45-25)+42.(38-18)

=78.20+42.20

=20.(78+42)

=20.120

=2400

Answer 5

C, 72.9x99+72+0.9 
=(72+0.9)x99+72+0.9 
=72x99+0.9x99+72+0.9 
=72x(99+1) + 0.9x(99+1) 
=72x100+0.9x100 
=7200+90 
=7290

Answer 6

d,3.4.4+1.7.8+3.4.2

=3.4.2.2+1.7.2.4+3.4.2

=6.4.2+7.4.2+3.4.2

=4.2.(6+7+3)

=8.16

=128