脱式计算,能简算的要简算. 98.9×998.53-(2.25+3.53)0.725÷0.5÷0.20.25×7×4×0.62.7×3.6+1.4×2.780.8×101-80.8.
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解:(1)98.9×99,
=98.9×(100-1),
=9890-98.9,
=9791.1;
(2)8.53-(2.25+3.53),
=8.53-3.53-2.25,
=5-2.25,
=2.75;
(3)0.725÷0.5÷0.2,
=0.725÷(0.5×0.2),
=0.725÷0.1,
=7.25;
(4)0.25×7×4×0.6,
=(0.25×4)×(0.6×7),
=1×4.2,
=4.2;
(5)2.7×3.6+1.4×2.7,
=2.7×(3.6+1.4),
=2.7×5,
=13.5;
(6)80.8×101-80.8,
=80.8×(101-1),
=80.8×100,
=8080;
解析分析:(1)(5)(6)运用乘法的分配律进行计算即可.(2)运用一个数减去两个数的和,可以用这个数分别减去这两个数.(3)运用一个数连续除以两个数,可以用这个数除以这两个数的积.(4)我们运用乘法的交换律、结合律进行解答即可.
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.