Tính nhanh 3,72 +2,05 + 6,28 + 7,95 = 1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90

0 bình luận về “Tính nhanh 3,72 +2,05 + 6,28 + 7,95 = 1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90”

1. a) 3,72 + 2,05 + 6,28 + 7,95

   = (3,72 + 6,28) + (2,05 + 7,95)

   = 10 + 10

   = 20

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

   = $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$ + $\frac{1}{10}$

   = $\frac{9}{10}$ 

   #chucbanhoctot

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2. a) 3,72 + 2,05 + 6,28 + 7,95

   = ( 3,72 + 6,28 ) + ( 2,05 + 7,95 ).

   = 10 + 10.

   = 20.

   b) 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

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