(689 + 875) + 125 = 689 + (875 + 125) = 689 + 1000 = 1689.

581 + (878 + 419) = (581 + 419) = 878 = 1000 + 878 = 1878.

a) (689 + 875) + 125

= 689 + (875 + 125)

= 689 + 1000 = 1689.

581 + (878 + 419)

= (581 + 419) = 878

= 1000 + 878 = 1878.

b)

c) 5,87 + 28,69 + 4,13

= (5,87 + 4,13) + 28,69

= 10 + 28,69

= 38,69.

83,75 + 46,98 + 6,25

= (83,75 + 6,25) + 46,98

= 90 + 46,98

= 136,98.

\(\frac{5}{6}+\frac{7}{12}=\frac{10}{12}+\frac{7}{12}=\frac{17}{12}\)

\(3+\frac{5}{7}=\frac{21}{7}+\frac{5}{7}=\frac{26}{7}\)

(689+875)+125=689+875+125=689+1000=1689

581+(878+419)=581+878+419=581+419+878=1000+878=1878

5,87+28,69+4,13=5,87+4,13+28,69=10+28,69=38,69

83,75+46,98+6,25=83,75+6,25+46,98=90+46,98=136,98

5/6 + 7/12 = 17/12

3 + 5/7 =  26/7

926,83 + 549,67 = 1476.5

(689 + 875) + 125 = 689 + (875 + 125) = 1689

581 + (878 + 419) = (581 + 419) + 878 = 1878

5,87 + 28,69 + 4,13 = (5,87 + 4,13) + 28,69 = 38,69

83,75 + 46,98 + 6,25 =( 83,75 + 6,25) + 46,98 = 136,98

a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

chúc bạn học tốt

A, 32 * 47 + 32 * 53 

  = 32 * ( 47 + 53 )

  = 32 * 100

  = 3200 .

B, 875 + 5375 : 25 - 875

  = 875 - 875 + 5375 : 25

  = 0 + 2115

  = 215 .

C, 5 * 25 * 2 * 16 * 4

  = ( 5 * 2 * 16 ) * ( 25 * 4 )

  = 160 * 100

  = 16000 .

125 x 333 + 125 x 333 + 125 x 334

= 125 x ( 333 + 333 + 334 )

= 125 x 1000

= 125000

125 ( 333 + 333 + 334 ) = 125 x 1000 = 125000

2 câu đấy à?

\(125+173+175+27=\left(125+175\right)+\left(173+27\right)=300+200=500\)

\(125\times75+125\times25=125\times\left(75+25\right)=125\times100=12500\)

125 x 12 + 12 x 874 + 12

=       ( 125 + 874 + 1 ) x 12

=            1000  x  12

=             12 000