×2+2÷1=4.85×2+4.85÷+4.85=(1+×3)÷2=5×3.5+0.729×=40×39=80×÷×=
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解:①×2+2÷1,
=,
=;
②4.85×2+4.85÷+4.85
=4.85×2+4.85×97+4.85×1,
=4.85×(2+97+1),
=4.85×100,
=485;
③(1+×3)÷2,
=(1+)÷2,
=×,
=1;
④5×3.5+0.729×,
=19.5+0.162,
=19.662;
⑤40×39,
=40×(39+),
=40×39+40×,
=40×39+39,
=1560+39,
=1599;
⑥80×÷×,
=80××800×,
=10.
解析分析:②、③变形之后可运用乘法分配律简算,其它题目按照先算乘除,再算加减,有括号的先算括号里面的顺序计算.
点评:乘法分配律是常用的简算方法,要会灵活运用.