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

Toán Lớp 6: tính nhanh: 53 x 39 + 47 x 39 – 53 x 21 – 47 x 21

Toán Lớp 6: tính nhanh:
53 x 39 + 47 x 39 – 53 x 21 – 47 x 21

Comments ( 2 )

  1. 53 xx 39 + 47 xx 39 – 53 xx 21 – 47 xx 21
    = 39 xx ( 53 + 47) – 21 xx ( 53 + 47 )
    = 39 xx 100 – 21 xx 100
    = 3900 – 2100
    = 1800
     

  2. 53 xx 39 + 47 xx 39 – 53 xx 21 – 47 xx 21
    =39 xx (53+47) – 21 xx (53+47)
    =39 xx 100 – 21 xx 100
    =100 xx (39-21)
    =100 xx 18
    =1800

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