用计算器探索规律

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,小数除法,用计算器探索规律,发布者：马春晖,2019.9.19,0.3636,4,11,0.4545,5,11,一、复习旧知,用计算器计算下面各题。,1,11,0.0909,2,11,0.1818,3,11,0.2727,二、探索新知,111,0.0909,2,11,0.1818,3,11,0.2727,4,11,0.3636,5,11,0.4545,你发现了什么规律？,它们的商都是循环小数。,1,11,0.0909,2,11,0.1818,3,11,0.2727,4,11,0.3636,5,11,0.4545,91,09,92,18,93,27,94,36,95,45,二、探索新知,你还发现了什么规律？,09,18,27,36,45,它们的循环节都是,9,的倍数。,被除数是几，循环节就是,9,的几倍。,它们的循环节都有两位。,1,2,3,4,5,1,2,3,4,5,不计算，用发现的规律直接写出下面几题的商。,6,11,0.5454,7,11,0.6363,8,11,0.7272,9,11,0.8181,想一想,611,的商是多少？,试试看：,1511,？,二、探索新知,1.3636,15,11,二、探索新知,可以这样想：,15,11,1,4,4,11,0.3636,15,11,1.3636,？,18,11,30,11,1,7,1.6363,2,8,2.7272,三、知识应用,6,0.7,6.6,6.7,6.66,66.7,6.666,666.7,1.,不计算，运用规律直接填出得数，再用计算器验算。,4.2,44.22,444.222,4444.2222,猜猜,6.66 66.7,的积是多少？你是怎么想的？,想一想,6.666666.7,整数部分有几个,4,，小数部分又是多少？,三、知识应用,3,7,3.3,6.7,3.33,66.7,3.333,666.7,3.3333,6666.7,3.33333,66666.7,21,22.11,222.111,2222.1111,22222.11111,222222.111111,3.333333,666666.7,2222222.1111111,你能用发现的规律接着写出下面一个算式吗？,2.,用计算器计算前,4,题，试着写出后,2,题的积。,1,7,2,7,3,7,4,7,5,7,6,7,0.142857142857,0.571428571428,0.714285714285,0.857142857142,三、知识应用,0.285714285714,0.428571428571,你发现了什么？,仔细观察，想一想，前,4,个算式商的相同之处是什么？不同之处又是什么？,你能用发现的规律把后面两道算式的商写出来吗？,都是循环小数。,循环节的数字都是,1,、,4,、,2,、,8,、,5,、,7,。,组成循环节的,6,个数字的排列顺序不同。,3.,用计算器计算下面各题。,四、布置作业,作业：第,37,页练习八，第,12,题。,