用喜欢的方法计算.
0.16×[1÷(2.1-2.09)]
?????????
2.5+2.8+2.2+6.5????????????????????????????
0.75×99.
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解:(1)0.16×[1÷(2.1-2.09)],
=0.16×[1÷0.01],
=0.16×100,
=16;
(2)×+÷5,
=×+×,
=×(+),
=×1,
=;
(3)2.5+2.8+2.2+6.5,
=(2.5+6.5)+(2.8+2.2),
=9+5,
=14;
(4)0.75×99,
=0.75×(100-1),
=75-0.75,
=74.25.
解析分析:(1)先算小括号内的,再算中括号内,最后算括号外的;(2)把除法改为乘法,运用乘法分配律简算;(3)运用加法交换律与结合律简算;(4)把99看作100-1,运用乘法分配律简算.
点评:考查了四则混合运算.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.