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

Toán Lớp 6: Bài 10: tính nhẩm A) 9.24.25 B)12.125.54 C)64.125.875 D)425.7.4-170.60 E)8.9.14+6+6.17.12+19.4.18

Toán Lớp 6: Bài 10: tính nhẩm
A) 9.24.25
B)12.125.54
C)64.125.875
D)425.7.4-170.60
E)8.9.14+6+6.17.12+19.4.18

Comments ( 1 )

  1. A) 9.24.25
    = 9.6.4.25
    = 9.6.(4.25)
    = 54.100
    =5400
    B)12.125.54
    = 3.4.125.54
    = (4.125) .3.54
    = 1000 . 81
    = 81000
    C)64.125.875
    = 8.8.125.875
    = ( 8.125).(8.875)
    = 1000.7000
    = 7000000
    D)425.7.4-170.60
    = (425.4).7 – 170.10.6
    = 1700.7 – 1700.6
    = 1700.7 – 1700.6
    = 1700 . ( 7-6)
    = 1700
    E)8.9.14+6+6.17.12+19.4.18
    = 2.4.9.14 + 6 + 2.3.17.3.4 + 19.4.2.9
    = 2.4.9.14 + 6 + 2.(3.3).17.4 + 19.4.2.9 
    = ( 2.4.9.14 + 2.9.17.4 + 19.4.2.9) + 6
    = [2.4.9 ( 14 + 17 + 19 )] + 6
    = [ 2.4.9.50] + 6 
    = [ ( 4.9).(50.2)] +6
    = [ 36 . 100 ] + 6
    = 3600 + 6
    =3606 

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