脱式计算,能简算的要简算. ①418+901÷17②÷+×③5-5×+④57.5-4.25-15.75 ⑤(+)×8+⑥×[1÷(-)].
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解:
①418+901÷17,
=418+53,
=471;
②÷+×,
=×+×,
=(+)×,
=1×,
=;
③5-5×+,
=5-2+,
=3+,
=3;
④57.5-4.25-15.75,
=57.5-(4.25+15.75),
=57.5-20,
=37.5;
⑤(+)×8+,
=×8+×8+,
=5++,
=5+(+),
=5+1,
=6;
⑥×[1÷(-)],
=×[1÷],
=×,
=3.
解析分析:①先算除法,再算加法;②根据乘法分配律进行计算;③先算乘法,再算减法,最后算加法;④根据连减的性质进行计算;⑤根据乘法分配律进行计算;⑥先算减法,再算除法,最后算乘法.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.