怎样算简便就怎样算.
①46×8-120÷15
②×+÷7
③6.28+7.13-(5.13+3.28)
④
⑤(12.5×8-40)÷0.6
⑥(-)×72.
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解:①46×8-120÷15,
=368-8,
=360;
②×+÷7,
=×+×,
=()×,
=1×,
=;
③6.28+7.13-(5.13+3.28),
=6.28+7.13-5.13-3.28,
=(6.28-3.28)+(7.13-5.13),
=3+2,
=5;
④,
=+×-×,
=+-,
=2-,
=;
⑤(12.5×8-40)÷0.6,
=(100-40)÷0.6,
=60÷0.6,
=100;
⑥(-)×72,
=×72-×72×72,
=30-8+27,
=22+27,
=49.
解析分析:②④⑥运用乘法分配律简算;③运用加法结合律简算;①⑤按照先算乘除,再算加减,有括号的先算括号里面的顺序计算.
点评:运算定律是常用的简便运算的方法,要熟练掌握,灵活运用.