(2012•哈尔滨模拟) 脱式计算,能简算的要简算:

1个回答

  • 解题思路:(1)依据减法的性质化原式为:4.67-2.98-0.67,再依据加法的结合律解答,

    (2)依据减法性质解答,

    (3)运用乘法交换律和结合律解答,

    (4)(5)(6)运用乘法分配律解答.

    (1)4.67-(2.98+0.67),

    =4.67-0.67-2.98,

    =4-2.98,

    =1.02;

    (2)[8/49]÷[[9/8]-([1/8]+[3/7])],

    =[8/49]÷[[9/8]−

    1

    8−

    3

    7],

    =[8/49]÷[1-[3/7]]

    =[8/49]÷[4/7],

    =[2/7];

    (3)8×0.4×12.5×2.5,

    =(8×12.5)×(0.4×2.5),

    =100×1,

    =100;

    (4)125×(8+0.8+0.08),

    =125×8+125×0.8+125×0.08,

    =1000+100+10,

    =1110;

    (5)1.89×0.9+0.189,

    =1.89×0.9+1.89×0.1,

    =1.89×(0.9+0.1),

    =1.89×1,

    =1.89;

    (6)23.8×99+2.38,

    =23.8×(100-1)+2.38,

    =23.8×100-23.8×1+2.38,

    =2380-23.8+2.38,

    =2356.2+2.38,

    =2358.58.

    点评:

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

    考点点评: 本题主要考查学生运用四则运算计算,以及运用定律和性质简算的能力.