1/10 + 2/20 + 3/30 + 4/40 + 5/50 + 6/60 + 7/70 + 8/80 + 9/90

= 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10

= 1/10 x 9

= 9/10

   1 / 10 + 2 / 20 + 3 / 30 + 4 / 40 + 5 / 50 + 6 / 60 + 7 / 70 + 8 / 80 + 9 / 90

= 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10 + 1 / 10

= 1 / 10 x 9

= 9 / 10

\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

\(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

\(=\frac{1}{10}\times9\)

\(=\frac{9}{10}\)

200 nha bạn

36+64+20+40+40=200

( 36 + 64 ) + ( 20 + 40 + 40 ) 

= 100 + 100

= 200

:))

20+20=40

30+30=60

40+40=80

50+50=100

20+20=40

30+30=60

40+40=80

50+50=100

20+20=40

30+30=60

40+40=80

50+50=100

K mink nha ! 

Để mình giúp bạn nha !!

A) 55

B) 550

a)=55

b)550

kb với mk nha

\(1+2+3+4+5+6+7+8+9+10\)\(10=55\)

\(10+20+30+40+50+60+70+80\)\(+90+100=550\)

K mình nhahải anh

Chúc bạn học giỏi

\(10+20+30+40+50+60+70+80+90+100\)

\(=\left(10+90\right)+\left(20+80\right)+\left(30+70\right)+\left(40+60\right)+100+50\)

\(=100+100+100+100+100+50\)

\(=550\)

 = ( 10 + 90 ) + ( 20 + 80) + ( 30 + 70 ) + ( 40 + 60 ) + 50 + 100

=  100            +       100     +        100    +       100       +     50 + 100

= 100 x 5 + 50

= 500 + 50

= 550

tk nhé 

lop 3

10+90=100

20+80=100

30+70=100

40+60=100

100    =100

..50....=  50

100X5+50=550

10 + 10 = 20

20 + 20 = 40

30 + 30 = 60

40 + 40 = 80

50 + 50 = 100

20

40

60

80

100

\(10+10=20\)

\(20+20=40\)

\(30+30=60\)

\(40+40=80\)

\(50+50=100\)

Tích là:

    40 * 50 * 60 = 120000

              Đáp số:120000

120000

40 x 50 x 60

= 200 x 60

= 12000

40

nho k

\(30+50-40=40\)

Dễ mà hoang phuc

30+50-40

=80-40

=40

tk nhe

= ( 60 + 50+40+30+20+10 ) x 2000 + 1500

= 210 x 2000 + 1500

=  420000 + 1500

= 421500

= 421500 nha bn, nhớ k mk nha

=421500