用简便方法计算 567+142+558546-378-1621458+999796+643-596475-303265+318+35.
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解:①567+142+558,
=567+(142+558),
=567+700,
=1267;
②546-378-162,
=546-(378+162),
=546-540,
=6;
③1458+999,
=1458+1000-1,
=2458-1,
=2457;
④796+643-596,
=796-596+643,
=200+643,
=843;
⑤475-303,
=475-300-3,
=175-3,
=172;
⑥265+318+35,
=265+35+318,
=300+318,
=618.
解析分析:①④⑥利用加法交换律与结合律进行简算;
②利用减法的性质简算;
③把999看做1000-1计算;
⑤把减303看做减300再减3计算.
点评:灵活运用加法交换律与结合律可以使计算简便,注意把接近整十整百的数看做整十整百也可也使计算简便.