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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Bài 1 tính nhanh a}1/21+2/21+3/21+4/21+5/21+-..+17/21+18/21+19/21+20/21 b}1/10+20/100+300/1000+4000/10000 c} 4/3×7 + 4/7×11 + 4/11×5

Toán Lớp 6: Bài 1 tính nhanh
a}1/21+2/21+3/21+4/21+5/21+……+17/21+18/21+19/21+20/21
b}1/10+20/100+300/1000+4000/10000
c} 4/3×7 + 4/7×11 + 4/11×5 + 4/15×19 + 4/19×23 + 4/23×27
BÀi 2 tính nhanh
a} 4823+1560+5177+8440
b} 10556+8074+9444+926+1000
c} 576+789+467+111
Bài 3 tính nhanh
21,251+6,058+0,749+1,042
1,53+5,039+12,47+5,691

Comments ( 1 )

  1. a.$\frac{1}{21}$+$\frac{2}{21}$ +$\frac{3}{21}$ +………..+$\frac{18}{21}$ +$\frac{19}{21}$ +$\frac{20}{21}$ 
    =$\frac{1+2+3+4+5+6+7+8…..+19+20}{21}$ 
    =$\frac{( 19 + 1 ) + ( 18 + 2 ) + ( 17 + 3 ) + … ( 11 + 9 ) + 20 + 10}{21}$ 
    =$\frac{20 + 20 + 20 + … + 20 + 20 + 10}{21}$ 
    =$\frac{210}{21}$ 
    =10
     b.$\frac{1}{10}$ +$\frac{20}{100}$ +$\frac{300}{1000}$ $\frac{4000}{10000}$ 
    =$\frac{1}{10}$ +$\frac{2}{10}$ +$\frac{3}{10}$ +$\frac{4}{10}$ 
    =$\frac{1+2+3+4}{10}$ 
    =$\frac{10}{10}$ 
    =1
    c.$\frac{4}{3 x 7}$ +$\frac{4}{7×11}$ +$\frac{4}{11×5}$ +$\frac{4}{15×19}$ +$\frac{4}{19×23}$ $\frac{4}{23×27}$ 
    =$\frac{1}{3}$ -$\frac{1}{7}$ +$\frac{1}{7}$ -$\frac{1}{11}$ +$\frac{1}{11}$ -$\frac{1}{15}$+ $\frac{1}{15}$ -$\frac{1}{19}$ +$\frac{1}{19}$ – $\frac{1}{23}$ +$\frac{1}{23}$ -$\frac{1}{27}$ 
    =$\frac{1}{3}$ – ($\frac{1}{7}$ +$\frac{1}{7}$ )-($\frac{1}{11}$ +$\frac{1}{11}$ )-($\frac{1}{15}$ – $\frac{1}{15}$ )-($\frac{1}{19}$ -$\frac{1}{19}$ )-$\frac{1}{23}$ -$\frac{1}{23}$)- $\frac{1}{27}$ 
    =$\frac{1}{3}$ -$\frac{1}{27}$
    =$\frac{8}{27}$ 
    Bài 2:
    a.
      4823 + 1560 + 5177 + 8440
    = ( 4823 + 5177 ) + ( 1560 + 8440 )
    =  10000 + 10000
    = 10000 x 2 
    = 20000
      b. 10556 + 8074 + 9444 + 926 + 1000
    = ( 10556 + 9444 ) + ( 8074 + 926) + 1000
    = 20000 + 9000 +1000
    = 20000 + 10000
    = 30000
       c.576+789+467+111
    = ( 789 + 111 ) + 567 + 467
    =  900  + 567 + 467
    = 1467 + 467
    = 1934
    Bài 3 
    a.
    21,251+6,058+0,749+1,042
    =(21,251+0,749)+(6,058+1,042)
    =22+7,1
    =29,1
    b.
    1,53+5,039+12,47+5,691
    =(1,53+12,47)+(5,039+5,691)
    =13+10,73
    =23,73
    Chúc bạn học tốt nhá 
    Vote tớ 5 sao ạ cảm ơn nhiều

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222-9+11+12:2*14+14 = ? ( )