56.358358…用簡(jiǎn)便方法記作________,保留一位小數(shù)約是________,保留兩位小數(shù)約是________.
56.
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5
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56.4 56.36
分析:56.358358…是循環(huán)小數(shù),循環(huán)節(jié)是358,簡(jiǎn)記法:在循環(huán)節(jié)的首位和末位的上面各記一個(gè)小圓點(diǎn);將此數(shù)保留一位小數(shù),就是精確到十分位,看百分位上的數(shù)是否滿5;將此數(shù)保留兩位小數(shù),就是精確到百分位,看千分位上的數(shù)是否滿5,再運(yùn)用“四舍五入”的方法求出近似數(shù)即可.
解答:56.358358…用簡(jiǎn)便方法記作:56.
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5
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;
保留一位小數(shù)約是56.4;
保留兩位小數(shù)約是56.36.
故答案為:56.
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5
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,56.4,56.36.
點(diǎn)評(píng):此題考查如何用簡(jiǎn)便形式表示循環(huán)小數(shù):找出循環(huán)節(jié),在循環(huán)節(jié)的首位和末位的上面各記一個(gè)小圓點(diǎn)即可;也考查了運(yùn)用“四舍五入”法求一個(gè)小數(shù)的近似值.