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.