题目内容
计算,能简算的一定要简算.
①5.81+8.3+4.19+11.7;
②18.5-3.21-4.79;
③0.25×17.3×0.4;
④3.54×0.29-0.29×2.54.
①5.81+8.3+4.19+11.7;
②18.5-3.21-4.79;
③0.25×17.3×0.4;
④3.54×0.29-0.29×2.54.
考点:小数四则混合运算,运算定律与简便运算
专题:运算顺序及法则
分析:(1)利用加法的交换律和结合律简算;
(2)运用减法的性质简算;
(3)运用乘法交换律简算;
(4)运用乘法分配律简算.
(2)运用减法的性质简算;
(3)运用乘法交换律简算;
(4)运用乘法分配律简算.
解答:
解:①5.81+8.3+4.19+11.7
=5.81+4.19+(8.3+11.7)
=10+20
=30;
②18.5-3.21-4.79
=18.5-(3.21+4.79)
=18.5-8
=10.5;
③0.25×17.3×0.4;
=0.25×0.4×17.3
=0.1×17.3
=1.73;
④3.54×0.29-0.29×2.54
=0.29×(3.54-2.54)
=0.29×1
=0.29.
=5.81+4.19+(8.3+11.7)
=10+20
=30;
②18.5-3.21-4.79
=18.5-(3.21+4.79)
=18.5-8
=10.5;
③0.25×17.3×0.4;
=0.25×0.4×17.3
=0.1×17.3
=1.73;
④3.54×0.29-0.29×2.54
=0.29×(3.54-2.54)
=0.29×1
=0.29.
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.
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