+6.85+1.6+ ÷+5.25× 3.5%×9.9.
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解:(1)+6.85+1.6+,
=8.4+6.85+1.6+2.15,
=(8.4+1.6)+(6.85+2.15),
=10+9,
=19;
(2)÷+5.25×,
=12.75×+5.25×,
=(12.75+5.25)×,
=18×,
=15;
(3)3.5%×9.9,
=3.5%×(10-0.1),
=3.5%×10-3.5%×0.1,
=0.35-0.0035,
=0.3465.
解析分析:(1)运用加法交换律和结合律简算;
(2)先把除法变成乘法,再运用乘法分配律简算;
(3)9.9分解成10-0.1,再运用乘法分配律简算.
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.