计算下面各题(能简算的要简算)(1)7.05×23.7+7.05×76.3(2)0.125×3.2×2.5(3)(12+

1个回答

  • 解题思路:(1)运用乘法分配律简算;

    (2)运用乘法结合律简算;

    (3)、(4)根据先算乘除,再算加减,有括号的先算括号里面的运算顺序计算.

    (1)7.05×23.7+7.05×76.3,

    =7.05×(23.7+76.3),

    =7.05×100,

    =705;

    (2)0.125×3.2×2.5,

    =0.125×8×0.4×2.5,

    =1×1,

    =1;

    (3)(12+23.1÷0.75)×0.4-5.12,

    =(12+30.8)×0.4-5.12,

    =42.8×0.4-5.12,

    =17.12-5.12,

    =12;

    (4)1.6×[(12-7.2)÷(0.84÷2.1)],

    =1.6×[4.8÷0.4],

    =1.6×12,

    =19.2.

    点评:

    本题考点: 小数四则混合运算.

    考点点评: 运算定律是常用的简便运算的方法,要熟练掌握,灵活运用;有些常用的乘法的积要记住,如:25×4=100,125×8=1000等.