五年级数学上册3.3小数的性质讲义苏教版.ppt

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 的 性 质,我买,1,枝,铅笔用,了,0.3,元,.,我买,1,块,橡皮,用了,0.30,元,.,橡皮和铅笔的单价相等吗,?,为什么,?,5,0.3,元是,3,角,0.30,元也是,3,角,所以,0.3,元,=0.30,元,.,0.3,是,3,个,0.1,也就是,30,个,0.01;,0.30,也是,30,个,0.01,所,0.3=0.30,。,0.3=0.30,这两个小数有什么不同,?,第二个小数末尾多了一个“,0”.,你发现了什么,?,小数末尾添上,0,小数的大小不变。,100,1000,100,10,100,10,1,10,1,=,=,从,上面的例子中,你发现了什么,?,0.100,米,0.10,米,0.1,米,=,=,小数的末尾添上“,0”,或去掉“,0”,，,小数的大小不变。这是小数的性质。,0.3=0.30,左边价,格中的哪,些“,0”,可以,去掉,?,牛奶,:2.80,元,面包,:4.00,元,汽水,:3.05,元,火腿肠,:0.65,元,合计,:10.50,元,根据小数的性质,通常可以去掉,小数末尾的“,0”,，把小数化简。,6,2.80,元,=,2.8,元,4.00,元,=,4,元,10.50,元,=,10.5,元,试,1.,不改变数的大小,把下面各数写成三位小数,.,2.,不改变数的大小,把下面各数写成两位小数,.,0.4=,2.800=,3.16=,10=,0.0300=,20.620=,一,试,0.,400,3.,160,10.,000,20.,62,0.,03,2.,80,练,一,练,1.,照样子在下面的方框里填上合适的小数,.,0,0.1,0,1,0.10,0.20,0.40,0.50,0.70,0.60,0.80,0.90,1.00,0.30,0.2,0.7,0.5,0.3,0.4,0.6,0.8,0.9,2.,先涂色表示下面各小数,再比一比。,0.5,0.50,2.,先涂色表示下面各小数,再比一比,.,0.5,0.50,2.,先涂色表示下面各小数,再比一比,.,0.5,0.50,=,2.,先涂色表示下面各小数,再比一比,.,0.5,0.05,2.,先涂色表示下面各小数,再比一比,.,0.5,0.05,2.,先涂色表示下面各小数,再比一比,.,0.5,0.05,用“,元,”作单位，把下面的钱数改写成两位小数。,2,元,5,角,7,角,1,元零,8,分,35,元,2.50,元,0.70,元,1.08,元,35.00,元,1.,下面各数中的哪些,0,可以去掉,哪些,0,不可以,去掉,?,为什么,?,1.80 0.250 703.050 17.000,60.0 0.060 300 80.040,2.,4.30,0.018,7.203,0.090,7.2030,0.09,4.300,0.180,把,相等的数,用线连起来,.,根据小数的性质,化简下面的小数,0.400 0.080 1.750 29.00,10.830 20.10 0.0350 80.040,0.400=,0.4,0.0350=,0.035,1.750=,1.75,29.00=,29,10.830=,10.83,20.10=,20.1,0.080=,0.08,80.040=,80.04,把下面各数改写成三位小数。,0.5400 30.6 80 1.0200 60.0,0.5040 3.60 8.0 1.20 0.0600,0.5400=0.,540,0.5040=0.,504,30.6=30.,600,3.60=3.,600,80=80.,000,8.0=8.,000,1.0200=1.,020,1.20=1.,200,60.0=60.,000,0.0600=0.,060,