计算,能简算的要简算:(1)1÷4÷8÷0.25÷12.5(2)9.75-5.42-(0.25+2.58)(3)8×2.7+6.2×1.4+3.5×8.6(4)[+(

发布时间:2020-08-09 15:38:32

计算,能简算的要简算:
(1)1÷4÷8÷0.25÷12.5
(2)9.75-5.42-(0.25+2.58)
(3)8×2.7+6.2×1.4+3.5×8.6
(4)[+(20-4.7)×6]÷102.2.

网友回答

解:(1)1÷4÷8÷0.25÷12.5,
=1÷(4×8×0.25×12.5),
=1÷[(4×0.25)×(8×12.5)],
=1÷(1×100),
=1÷100,
=0.01;

(2)9.75-5.42-(0.25+2.58),
=9.75-5.42-0.25-2.58,
=(9.75-0.25)-(5.42+2.58),
=9.5-8,
=1.5;

(3)8×2.7+6.2×1.4+3.5×8.6,
=8.6×2.7+6.2×1.4+3.5×8.6,
=8.6×2.7+3.5×8.6+6.2×1.4,
=(2.7+3.5)×8.6+6.2×1.4,
=6.2×8.6+6.2×1.4,
=6.2×(8.6+1.4),
=6.2×10,
=62;

(4)[+(20-4.7)×6]÷102.2,
=[+15.3×6]÷102.2,
=[+×]÷102.2,
=[+102]÷102.2,
=102.2÷102.2,
=1.
解析分析:(1)先根据连续除以几个数等于除以这几个数的积简算,再运用乘法结合律简算;
(2)先根据减去两个数的和等于连续减去这两个数以及加法结合律简算;
(3)先运用加法结合律,再两次运用乘法分配律简算;(4)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:简便运算的方法有时可以结合使用,需要把部分算式看成一个整体,再运用简算的方法简算.
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