题目内容
用简便方法计算.12%
301×79
125×72×4
728×79十272×79
8.59+2.57+3.43+5.47
49.62+27.17-19.62
1546-(546-239)
301×79
125×72×4
728×79十272×79
8.59+2.57+3.43+5.47
49.62+27.17-19.62
1546-(546-239)
分析:(1)应用乘法分配律简算;
(2)应用乘法结合律简算;
(3)应用乘法分配律简算;
(4)应用加法结合律简算;
(5)应用加法交换律简算;
(6)应用减法的简便运算来解决问题.
(2)应用乘法结合律简算;
(3)应用乘法分配律简算;
(4)应用加法结合律简算;
(5)应用加法交换律简算;
(6)应用减法的简便运算来解决问题.
解答:解:(1)301×79,
=(300+1)×79,
=300×79+1×79,
=23700+79,
=23779;
(2)125×72×4,
=(125×4)×72,
=500×72,
=36000;
(3)728×79十272×79,
=79×(728+272),
=79×1000,
=79000;
(4)8.59+2.57+3.43+5.47,
=8.59+(2.57+3.43)+5.47,
=8.59+6+5.47,
=20.06;
(5)49.62+27.17-19.62,
=49.62-19.62+27.17,
=30+27.17,
=57.17;
(6)1546-(546-239),
=1546-546+239,
=1000+239,
=1239.
=(300+1)×79,
=300×79+1×79,
=23700+79,
=23779;
(2)125×72×4,
=(125×4)×72,
=500×72,
=36000;
(3)728×79十272×79,
=79×(728+272),
=79×1000,
=79000;
(4)8.59+2.57+3.43+5.47,
=8.59+(2.57+3.43)+5.47,
=8.59+6+5.47,
=20.06;
(5)49.62+27.17-19.62,
=49.62-19.62+27.17,
=30+27.17,
=57.17;
(6)1546-(546-239),
=1546-546+239,
=1000+239,
=1239.
点评:此题考查了运算定律与简便运算,认真观察,找出规律是解决此题的.
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