考点:整数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)根据乘法交换律和结合律简算;
(2)(4)(11)运用乘法分配律简算;
(3)把404分解成400+4,再运用乘法分配律简算;
(5)根据除法的性质简算;
(6)先算乘法,再算减法;
(7)根据减法的性质简算;
(8)先把88分解成8×11,再运用乘法结合律简算;
(9)根据除法的性质简算;
(10)根据加法交换律和加法结合律简算;
(12)根据加法交换律简算.
解答:
解:(1)8×(29×125)
=8×125×29
=1000×29
=29000;
(2)156×101-156
=156×(101-1)
=156×100
=15600;
(3)404×25
=(400+4)×25
=400×25+4×25
=10000+100
=10100;
(4)85×199+85
=85×(199+1)
=85×200
=17000;
(5)420÷(5×7)
=420÷7÷5
=60÷5
=12;
(6)100×27-27
=2700-27
=2673;
(7)168-52-48
=168-(52+48)
=168-100
=68;
(8)125×88
=125×(8×11)
=125×8×11
=1000×11
=11000;
(9)1300÷25÷4
=1300÷(25×4)
=1300÷100
=13;
(10)37+125+63+175
=(37+63)+(125+175)
=100+300
=400;
(11)75×56-56×25
=56×(75-25)
=56×50
=2800;
(12)688-534+112
=688+112-534
=800-534
=266.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.