小数的意义和性质

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,*,小数的意义和性质的,复习课,小学数学人教实验版第七单元,芙蓉区浏正街小学 陈 凡,（一）小数的计数单位和进率,知识点：,1,、,小数的,计数单位,是,十分之一,、,百分之一,、,千分之一,分别写作,0.1,、,0.01,、,0.001,2,、,每,相邻,两个计数单位间的,进率,是,10,。,练习题：,（,1,）说出下面各小数的意义,0.3,0.03,0.003,意义,:0.3,里面有,3,个,0.1,0.06,0.21,2.1,20.705,（一）小数的计数单位和进率,知识点：,1,、,小数的,计数单位,是,十分之一,、,百分之一,、,千分之一,分别写作,0.1,、,0.01,、,0.001,2,、,每,相邻,两个计数单位间的,进率,是,10,。,练习题：,（,2,）说出下面各小数的计数单位,0.3,0.03,0.003,计数单位是,0.1,0.06,0.21,0.01,0.001,0.01,0.01,（二）小数的性质和移动,知识点：,1,、,小数的,末尾,添上”,0”,或去掉”,0”,小数的,大小不变,练习题,不改变数的大小,下面数中的哪些”,0”,可以去掉,哪些”,0”,不能去掉,?,为什么,?,3.90,米,0.30,元,500,米,1.80,元,0.70,米,0.04,元,600,千克,20.20,米,可以去掉的”,0”,是,末尾的,0,（二）小数的性质和移动,知识点：,1,、,小数的,末尾,添上”,0”,或去掉”,0”,小数的,大小不变,练习题,如果在下面各数的末尾添”,0”,哪些数的大小不变,哪些数的大小有变化,?,3.4,18,0.06,700,908,104.03,150,10.01,3.0,42.00,在小数部分的末尾添”,0”,（二）小数的性质和移动,知识点：,2,、,小数点,向右,移动,1,位,小数就,扩大,到原数的,10,倍,移动,2,位,小数就,扩大,到原数的,100,倍,移动,3,位,小数就,扩大,到原数的,1000,倍,小数点,向左,移动,1,位,小数就,缩小,原数的,10,倍,移动,2,位,小数就,缩小,原数的,100,倍,移动,3,位,小数就,缩小,原数的,1000,倍,练习题：,0.25,(),到原数的,(),倍,2.5,扩大,10,(),缩小,了,10,倍,0.001,扩大,到原数的,100,倍,0.1,缩小,了,100,倍,（二）小数的性质和移动,知识点：,2,、,小数点,向右,移动,1,位,小数就,扩大,到原数的,10,倍,移动,2,位,小数就,扩大,到原数的,100,倍,移动,3,位,小数就,扩大,到原数的,1000,倍,小数点,向左,移动,1,位,小数就,缩小,原数的,10,倍,移动,2,位,小数就,缩小,原数的,100,倍,移动,3,位,小数就,缩小,原数的,1000,倍,练习题：,30.5,扩大,到原数的,10,倍,3.05,缩小,了,10,倍,15.3,扩大,到原数的,100,倍,0.153,缩小,了,100,倍,练习题：,1,、填上适当的数,(1),把,3.6,的小数点向,左,移动一位是,(),(2),把,3.14,的小数点向,左,移动两位是,(),(3),把,0.03,扩大到它的,(),倍是,30,(4),把,42,缩小,(),倍是,0.042,0.36,0.0314,1000,1000,2,、把,6.25,改写成下面的数,它的大小各有什么变化,?,62.5 0.625 625 0.0625,把,6.25,的,小数点,向,右,移动了,一,位,扩大,了原数的,10,倍,得到,62.5,