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

Toán Lớp 6: tính nhanh 66.65-65.64+64.63-63.62+-+4.3-3.2+2.1

Toán Lớp 6: tính nhanh
66.65-65.64+64.63-63.62+….+4.3-3.2+2.1

Comments ( 2 )

  1. 66.65 – 65.64+ 64.63 – 63.62 + …. + 4.3 – 3.2 + 2.1
    = 65(66-64) +63(64-62) +…..+3(4-2) +2
    = 2.65 + 63.2 +….+ 3.2 + 2
    = 2.(65 + 63 + 61 +….+ 3 + 1)
    = 2.1089
    = 2178

  2. A= 66.65 – 65.64+ 64.63 – 63.62 + …. + 4.3 – 3.2 + 2.1
    A=65(66-64) +63(64-62) +…..+3(4-2) +2
    A=2.65+63.2+….+3.2+2
    A=2.(65+63+61+….+3+1)
    A=2.1089
    A=2178
    Xin hay nhất cho nhóm !
     

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