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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,小数点移动,口算,215,10=,79,10=,502,10=,800,10=,324,100=,556,100=,17,1000=,30,1000=,2150,790,5020,8000,32400,55600,17000,30000,一个小数乘,10,,,如何计算?,10,个,0.001,是多少?,10,个,0.01,是多少?,10,个,0.1,是多少?,0.00110=0.01,0.0110=0.1,0.110=1,仔细观察,得数的小数点和原来有变化吗?,一个小数乘,10,,怎么计算呢?,一个小数乘,10,,只要将小数点向右移动一位。,一个小数乘,100,,怎么计算呢?,一个小数乘,1000,,怎么计算呢?,1.41100=,1.411000=,141,1410,预习作业:计算器验证,0.121000=,120,位数不够时,可以用“,0,”补足,练习:,(,1,),0.310=,0.3100=,0.3 1000=,(,2,),0.45()=4.5,0.45()=45,0.45()=4500,3,30,300,10,100,10000,一个小数除以,10,、,100,、,1000,的除法,怎样计算啊?,练习:,5.610,0.0910=,9810,0.57100,65100,0.9100,3651000=,10.21000=,2.971000,0.56,0.009,9.8,0.0057,0.65,0.009,0.365,0.0102,0.00297,当一个数除以,10,,,100,,,1000,;觉得不方便时,可以往前补上几个“,0,”,然后移位就方便了。,一、填空,3.14,(),10,小数点向,移动,位,37.8,(),1000,小数点向,移动,位,(),34.8,(),小数点向左移动两位,31.4,右,一,0.0378,左,三,3480,100,7.34 734,小数点向,移动,位,右,两,(),100,二、根据小数点的移动,正确填写运算符号及数。,8.73,87.3,0.873,0.00873,8730,10,100,100,1000000,1000,1,、去掉小数,8.7,的小数点,相当于原数()。,10,100,10,100,三、选择题,2,、将,50.3,的小数点先向右移动两位后,再向左移动三位,得数是()。,0.503,5.03,50.3,503,3,、,把小数,0.9,的小数点向右移动两位,再向左移动 三位,新数是原数的()倍。,0.1 10 100 1000,4,、一个数除以,1000,后,再乘,10,得,3.27,,原数是 ()。,0.327 32.7 327 3270,5,、在,7.1,的末尾添上两个,“,0,”,,()。,得数是原数的,100,倍,得数是原数的,2,倍,得数等于原数,得数是原数的,0.01,倍,总结:在小数性质的基础上,又学了移动小数点。注意运算符号,向哪边移动小数点。,
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