题目内容
用简便方法计算.
(1)56.78-35.9-5.78-4.1
(2)6.38×9.9+33×3.62×0.3.
(1)56.78-35.9-5.78-4.1
(2)6.38×9.9+33×3.62×0.3.
分析:(1)56.78-35.9-5.78-4.1,根据减法的运算性质进行简算;
(2)6.38×9.9+33×3.62×0.3,将原式转化为:6.38×9.9+9.9×3.62,再运用乘法分配律简算.
(2)6.38×9.9+33×3.62×0.3,将原式转化为:6.38×9.9+9.9×3.62,再运用乘法分配律简算.
解答:解:(1)56.78-35.9-5.78-4.1
=56.78-5.78-(35.9+4.1)
=51-40
=11;
(2)6.38×9.9+33×3.62×0.3
=6.38×9.9+9.9×3.62
=(6.38+3.62)×9.9
=10×9.9
=99.
=56.78-5.78-(35.9+4.1)
=51-40
=11;
(2)6.38×9.9+33×3.62×0.3
=6.38×9.9+9.9×3.62
=(6.38+3.62)×9.9
=10×9.9
=99.
点评:此题考查的目的是理解掌握减法的运算性质和乘法的运算定律,并且能够灵活运用这些运算性质和运算定律进行简便计算.
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