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

Toán Lớp 4: a. 815 – 23 – 77 + 185 b. 3145 + 2496 + 5347 + 7504 + 4653 c. 1 + 3 + 5 + 7 + 9+ 11 + 13 + 15 + 17 + 19

Toán Lớp 4: a. 815 – 23 – 77 + 185
b. 3145 + 2496 + 5347 + 7504 + 4653
c. 1 + 3 + 5 + 7 + 9+ 11 + 13 + 15 + 17 + 19

Comments ( 2 )

  1. a) 815 – 23 – 77 + 185
    = ( 815 + 185 ) – ( 23 + 77 )
    = 1000 – 100
    = 900
    $\text{b) 3145 + 2496 + 5347 + 7504 + 4653}$
    $\text{= ( 2496 + 7504 ) + ( 5347 + 4653 ) + 3145}$
    $\text{= 10 000 + 10 000 + 3145}$
    $\text{= 23 145}$
    $\text{c) 1 + 3 + 5 + 7 + 9+ 11 + 13 + 15 + 17 + 19}$
    $\text{= ( 1 + 19 ) + ( 3 + 17 ) + ( 5 + 15 ) + ( 7 + 13 ) + ( 9 + 11 )}$
    $\text{= 20 + 20 + 20 + 20 + 20}$
    $\text{= 20 × 5}$
    $\text{= 100}$
    $\text{Xin hay nhất và 5 sao ạ}$

  2. a, 815-23-77+185
    =(815+185)-(23+77)
    =1000-100
    =900
    b, 3145+2496+5347+7504+4653
    =(2496+7504)+(5347+4653)+3145
    =10000+10000+3145
    =23145
    c, 1+3+5+7+9+11+13+15+17+19
    =(1+19)+(3+17)+(5+15)+(7+13)+(9+11)
    =20+20+20+20+20
    =100

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