五年级上册数学小数除法用计算器探索规律

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,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。,311,，商是循环小数，循环节是,27,，,27,是被除数,3,的,9,倍。,411,，商是循环小数，循环节是,36,，,36,是被除数,4,的,9,倍。,511,，商是循环小数，循环节是,45,，,45,是被除数,5,的,9,倍。,111，商是循环小数，循环节是09，9是被除数1的9倍。,211,，商是循环小数，循环节是,18,，,18,是被除数,2,的,9,倍。,1,11,0.0909,2,11,0.1818,3,11,0.2727,4,11,0.3636,5,11,0.4545,循环节是,09,循环节是,18,循环节是,27,循环节是,36,循环节是,45,二、探索新知,你还发现了什么规律？,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,8 11,的商是多少？,你是怎么想出,9 11,0.8181,这个答案的？,二、探索新知,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,6.666 666.7,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。,112234=,111222334=,111122223334=,111112222233334=,33,333,3333,33333,33333333,112234=33,111222334=333,111122223334=3333,111112222233334=33333,积都是由“,3”,写成的；而且“,3”,的个数与被除数中“,1”,、“,2”,的个数相等。,商都比除数小,1,，（或 “除数,-1”,就是商）,商中的“,3”,的个数比除数中,3,的个数多一个。,