教育专题：百分数、小数和分数的互化

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,*,1.,把下面的小数化成分数,再说一说小数化分数的方法,.,0.45 1.2 0.367,小数,先化成分母是,10,100,1000,的分数,再约分,分数,2.,先把下面的分数化成小数,再说说分数化小数的方法,.,分数,小数,用分子除以分母,3.,把下面各分数改写成百分数,.,25,3,100,21,20,9,100,9,100,35,100,112,100,1.8,你,能,直接判断,7,4,57.1%,5.7,的大小吗,?,如果,要比较这些数的大小,需要做些什么,?,例,1.,把,0.25,1.4,0.123,化成百分数,.,0.25,100,25,=,25%,1.4,10,4,=,10,14,=,100,140,=,140%,0.123,1000,123,=,100,12.3,=,12.3%,小数,百分数,把小数点向右移动两位,同时在后面添上,%,0.25=25%1.4=140%0.123=12.3%,=,=,1,=,小数,把小数点向右移动两位,同时在后面添上,%,百分数,例,2.,把,27%,124%,0.4%,化成小数,。,27%=,100,27,=27,100=0.27,124%=,100,124,=,124,100=,0.4%=,100,0.4,=,0.4,100=,0.004,27%=0.27 124%=1.240.4%=0.004,把,%,去掉,同时把小数点向左移动两位,0.27,1.24,2.,把下面各百分数化成小数。,15%80%3.5%,1.,把下面各小数化成百分数。,0.38 1.05 0.055 3,做一做,:,例,3.,把,4,3,6,1,1,5,3,化成百分数,.,4,3,=,0.75,=,75%,4,3,=,100,75,=,75%,6,1,0.167,=,16.7%,1,5,3,=,1.6=160%,分数,百分数,通常先化成小数,再化成百分数。,将,下列分数化成百分数,.,将下列百分数化成分数,.,5,1,8,1,1,3,1,14%2.5%120%,做一做,:,例,4.,你,能将,17%,40%,12.5%,化成分数吗,?,17%=,100,17,40%,=,100,40,=,5,2,12.5%=,100,12.5,=,1000,125,=,8,1,百分数,分数,化成分母是,100,的分数,能约分的要约分,小数,百分数,小数点向右移动两位,添上,%,去掉,%,小数点向左移动两位,.,分数,通常先化成小数,再化成百分数,.,百分数,改写成分母是,100,的分数,能约分的要约分,.,