怎样简便就怎样计算. 355+260+140+245

1个回答

  • 解题思路:(1)运用加法交换律与结合律简算;

    (2)把99看作100-1,运用乘法分配律简算;

    (3)把125看作100+25,运用乘法分配律简算;

    (4)(7)运用乘法分配律简算;

    (5)把8看作2×4,运用乘法交换律与分配律简算;

    (6)运用加法交换律与结合律简算.

    (1)355+260+140+245,

    =(355+245)+(260+140),

    =600+400,

    =1000;

    (2)102×99,

    =102×(100-1),

    =10200-102,

    =10200-100-2,

    =10100-2,

    =10098;

    (3)2×125,

    =2×(100+25),

    =200+50,

    =250;

    (4)382×101-382,

    =382×(101-1),

    =382×100,

    =38200;

    (5)4×60×50×8,

    =4×60×50×2×4,

    =240×100×4,

    =240×4×100,

    =960×100,

    =96000;

    (6)645-180-245,

    =(645-245)-180,

    =400-180,

    =220;

    (7)35×8+35×6-4×35,

    =35×(8+6-4),

    =35×10,

    =350.

    点评:

    本题考点: 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.