脱式计算.①8.82×15-100 ②15.8-[7/18]+14.2-[11/18], ③21.6-0.8×4÷0.8

1个回答

  • 解题思路:①按运算顺序计算,先算乘法,再算减法;

    ②运用加法交换律与结合律以及减法的性质简算;

    ③按运算顺序计算,先算0.8×4÷0.8×4,按运算顺序从左向右依次计算,最后算减法;

    ④运用乘法分配律简算;

    ⑤按运算顺序计算,先算除法,再按顺序从左向右依次计算;

    ⑥中括号内运用乘法分配律简算.

    ①8.82×15-100,

    =132.3-100,

    =32.3;

    ②15.8-[7/18]+14.2-[11/18],

    =(15.8+14.2)-([7/18]+[11/18]),

    =30-1,

    =29;

    ③21.6-0.8×4÷0.8×4,

    =21.6-3.2÷0.8×4,

    =21.6-16,

    =5.6;

    ④3×3.7+3.6+5.3×3,

    =(3.7+5.3)×3+3.6,

    =9×3+3.6,

    =27+3.6,

    =30.6;

    ⑤5+0.45÷0.9-1.75,

    =5+0.5-1.75,

    =5.5-1.75,

    =3.75;

    ⑥1110÷[56×([3/7]-[3/8])],

    =1110÷[56×[3/7]-56×[3/8]],

    =1110÷[24-21],

    =1110÷3,

    =370.

    点评:

    本题考点: 小数四则混合运算;运算定律与简便运算;分数的简便计算;分数的四则混合运算.

    考点点评: 考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.