(1)9.43+0.78-2.43(2)1+0.45÷0.9-0.5
(3)0.9+99×0.9(4)+( +)×
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解:(1)9.43+0.78-2.43,
=9.43-2.43+0.78,
=7+0.78,
=7.78;
(2)1+0.45÷0.9-0.5,
=1+0.5-0.5,
=1+(0.5-0.5),
=1+0,
=1;
(3)0.9+99×0.9,
=0.9×(1+99),
=0.9×100,
=90;
(4)+(+)×,
=+×,
=+,
=1.
解析分析:(1)运用加法交换律简算;
(2)先算除法,再运用加法结合律简算;
(3)运用乘法分配律简算;
(4)先算小括号里面的加法,再算括号外的乘法,最后括号外的加法.
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.