用简便方法计算下列各题 25×(40×32); (5×7)×80; 8×14×125×6; 16×25×5×4; 25×

1个回答

  • 解题思路:(1)(14)运用乘法结合律简算.

    (2)(3)(4)(5)(8)运用乘法交换律与结合律简算.

    (6)把598看作600-2,运用减法的性质简算.

    (9)运用加法交换律与结合律简算.

    (11)(12)(13)(15)运用乘法分配律简算.

    (1)25×(40×32)

    =(25×40)×32

    =1000×32

    =32000

    (2)(5×7)×80

    =(5×80)×7

    =400×7

    =2800

    (3)8×14×125×6

    =(8×125)×(14×6)

    =1000×84

    =84000

    (4)16×25×5×4

    =(16×5)×(25×4)

    =90×100

    =9000

    (5)25×13×4

    =(25×4)×13

    =100×13

    =1300

    (6)2843-598

    =2843-(600-2)

    =2843-600+2

    =2245

    (7)4×8×25×125

    =(4×25)×(8×125)

    =100×1000

    =100000

    (8)259+468+741+532

    =(259+741)+(468+532)

    =1000+1000

    =2000

    (9)36×25

    =9×4×25

    =9×(4×25)

    =9×100

    =900

    (10)12×15+12×35

    =12×(15+35)

    =12×50

    =600

    (11)31×128-28×31

    =31×(128-28)

    =31×100

    =3100

    (12)(25+250)×4

    =25×4+250×4

    =100+1000

    =1100

    (13)(125×125)×8

    =125×(125×8)

    =125×1000

    =125000

    (14)([7/12]-[1/5])×60

    =60×[7/12]-[1/5]×60

    =35-12

    =23

    (15)[4/7]×[6/13]+[3/7]×[6/13]

    =([4/7]+[3/7])×[6/13]

    =1×[6/13]

    =[6/13]

    点评:

    本题考点: 运算定律与简便运算.

    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.