题目内容
用简便方法计算
①0.4×1.36×2.5 ②0.45×101 ③3.8×4.6+4.6×6.2.
①0.4×1.36×2.5 ②0.45×101 ③3.8×4.6+4.6×6.2.
分析:①0.4×1.36×2.5,运用乘法交换律和结合律进行简算;
②0.45×101,运用乘法分配律进行简算;
③3.8×4.6+4.6×6.2. 运用乘法分配律进行简算.
②0.45×101,运用乘法分配律进行简算;
③3.8×4.6+4.6×6.2. 运用乘法分配律进行简算.
解答:解:①0.4×1.36×2.5,
=1.36×(0.4×2.5),
=1.36×1,
=1.36;
②0.45×101,
=0.45×100+0.45×1,
=45+0.45,
=45.45;
③3.8×4.6+4.6×6.2,
=(3.8+6.2)×4.6,
=10×4.6,
=46.
=1.36×(0.4×2.5),
=1.36×1,
=1.36;
②0.45×101,
=0.45×100+0.45×1,
=45+0.45,
=45.45;
③3.8×4.6+4.6×6.2,
=(3.8+6.2)×4.6,
=10×4.6,
=46.
点评:此题考查的目的是理解掌握乘法的运算定律,并且能够灵活运用乘法的运算定律对小数四则混合运算进行简便计算.
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