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单击此处编辑母版标题样式,#,单击此处编辑母版标题样式,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,单击此处编辑母版标题样式,*,分数与小数的互化,人教版版五年级数學下册,有两位同学进行登山比赛,从山下到,山顶,甲用了 时,乙用了,0.8,时,哪位,同学登得快?,3,4,3,4,0.8,(),()=,(),(),()=,(),(),()=,(),0.3,3,10,0.25,0.4,25,100,4,10,用小数和分数表达下面每個图中的涂色部分。,(1)0.6裏面有6個()分之壹,,它表达()分之()。,(2)0.05裏面有5個()分之壹,,它表达()分之()。,(3)0.007裏面有7個()分之壹,,它表达()分之()。,(4)4.27表达()又(),分之()。,拾,拾,六,百,百,五,仟,仟,七,四,百,二拾七,分数与小数的互化,把,0.7,、,0.03,、,1.21,、,0.425,化成分数。,0.7=,想:0.7是拾分之七。,7,10,0.03=,想:,0.03,是百分之三。,3,100,1.21=,想:1.21是壹又百分,之二拾壹。,21,100,1,0.425=,想:0.425是仟分之,四百二拾五。,425,1000,17,40,=,分数与小数的互化,請你观测例6中的題目,讨论:,小数化分数有什么简便的措施?,0.7=,7,10,0.03=,3,100,1.21=,21,100,1,0.425=,425,1000,17,40,=,提醒:用什么数作分母?用什么数作分子?,7,7,3,3,425,425,21,21,分数与小数的互化,請你观测例6中的題目,讨论:小数化分数有什么简便的措施?,小数化分数,本来有几位小数,就在1背面写几种0作分母,把本来的小数去掉小数點作分子;化成分数後,能约分,的要约分。,随堂练习:,(,1,)把,0.6,、,0.08,化成分数。,(,2,)把,2.41,、,3.06,、,1.25,化成分数。,巩固练习:,(,1,)把下面小数化成分数,0.9=0.17=0.07=,0.6=0.25=0.04=,1.2=2.375=3.05=,(,2,)比较大小,【1】0.89,和,【2】3.39,和,【3】0.376,、,17,20,19,50,2,5,2,5,3,9,10,17,100,7,100,6,10,3,5,25,100,1,4,1,25,1,5,1,1,8,2,1,20,3,=,=,分数化小数,复习导入,(1)在()裏填上合适的数。,【1】=()()【2】=()(),【3】=()()【4】=()(),4,5,1,6,4,9,8,15,4,5,1,6,4,9,8,15,(,2,)分数与除法的关系:,被除数,除数,=,被除数,除数,分子,分母,(,3,)把小数化成分数:,0.75=,0.8=,75,100,3,4,=,8,10,4,5,=,分数与小数的互化,把 、化成小数。,7,10,67,100,3,100,1,0.7,0.67,1.,0,3,3,100,1,=,7,10,=,67,100,=,分数与小数的互化,分母是10,100,1000,的分数化小数,可以直接去掉分母,看分母中1背面有几种0,就在分子中從最终壹位起向左数出几位,點上小数點。,分数与小数的互化,把下面的分数化成小数:,31,100,3,10,23,100,1,25,1000,2,把 、化成小数。,3,8,7,20,9,40,1,3,5,9,(除不尽的保留两位小数。),1,把下面的分数化成小数。,1,4,1,8,3,5,1,5,87,100,=0.25,=0.2,=0.6,=0.125,=0.87,19,20,5,8,9,20,5,2,5,1,20,=,=,
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