下面各题怎样简便就怎样算.(1)3.7×99+3.7 (2)[3/4]×7.7+3.3×0.75-75% (3)5.93

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  • 解题思路:(1)(6)运用乘法分配律简算;(2)把分数和百分数化为小数,运用乘法分配律简算;(3)运用加法交换律与结合律简算;(4)先算括号内的除法,再算括号内的减法,最后算括号外的乘法;(5)运用除法的性质简算.

    (1)3.7×99+3.7,

    =3.7×(99+1),

    =3.7×100,

    =370;

    (2)[3/4]×7.7+3.3×0.75-75%,

    =0.75×7.7+3.3×0.75-0.75,

    =0.75×(7.7+3.3-1),

    =0.75×10,

    =7.5;

    (3)5.93+0.64+0.07+0.36,

    =(5.93+0.07)+(0.64+0.36),

    =6+1,

    =7;

    (4)(7.9-3.06÷0.68)×1.5,

    =(7.9-4.5)×1.5,

    =3.4×1.5,

    =5.1;

    (5)78÷2.5÷0.4,

    =78÷(2.5×0.4),

    =78÷1,

    =78;

    (6)105×([1/3]+[1/5]),

    =105×[1/3]+105×[1/5],

    =35+21,

    =56.

    点评:

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

    考点点评: 完成本题要注意分析式中数据,运用合适的简便方法计算.