混合运算.(能简算的要简算)
198-(98+37 ) 34×102 ×40-÷80.3-33.3×0.5÷0.37 (-)×12÷0.1 ×[÷(+)].
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解:(1)198-(98+37 ),
=198-98-37,
=100-37,
=63;
(2)34×102,
=34×(100+2),
=34×100+34×2,
=3400+68,
=3468;
(3)×40-÷,
=×40-×40,
=(-)×40,
=×40,
=5;
(4)80.3-33.3×0.5÷0.37,
=80.3-16.65÷0.37,
=80.3-45,
=35.3;
(5)(-)×12÷0.1,
=(-)×(12×10),
=(-)×120,
=×120-×120,
=90-80,
=10;
(6)×[÷(+)],
=×[÷],
=××,
=×,
=.
解析分析:(1)先算小括号里面的加法,再算括号外的减法;
(2)把102分解成100+2,再运用乘法分配律简算;
(3)先把除法变成乘法,再运用乘法分配律简算;
(4)先算乘法,再算除法,最后算减法;
(5)先把除法变成乘法,然后运乘法结合律简算把后两个数结合在一起,然后运用乘法分配律简算;
(6)先算小括号里面的加法,再把除法变成乘法,运用乘法结合律简算.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.