用你喜欢的方法计算下面各题.①23.8−79+6.2−119②37.5+12.5÷2.5×4③(79+23×56)÷41

1个回答

  • 解题思路:(1)运用加法结合律以及减法性质解答,

    (2)(3)依据四则运算计算方法,先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的解答.

    (4)(6)运用乘法分配律解答,

    (5)化3.2=8×0.4,再运用乘法结合律解答.

    (1)23.8−

    7

    9+6.2−

    11

    9],

    =(23.8+6.2)-([7/9]+[11/9]),

    =30-2,

    =28;

    (2)37.5+12.5÷2.5×4,

    =37.5+5×4,

    =37.5+20,

    =57.5;

    (3)(

    7

    9+

    2

    5

    6)÷

    4

    15,

    =([7/9]+[5/9])÷

    4

    15,

    =[4/3]÷

    4

    15,

    =5;

    (4)(

    5

    17+

    4

    13)×13×17,

    =[5/17]×13×17+[4/13]×13×17,

    =65+68,

    =133;

    (5)125×3.2×25,

    =(125×8)×(0.4×25),

    =1000×10,

    =10000;

    (6)777×[7/100+444×0.09+333×0.05,

    =111×(7×

    7

    100]+4×0.09+3×0.05),

    =111×(0.49+0.36+0.15),

    =111×1,

    =111.

    点评:

    本题考点: 整数、分数、小数、百分数四则混合运算;运算定律与简便运算.

    考点点评: 考查了运算定律与简便运算,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律简便计算.