1、小 數(shù) 乘 法 復(fù) 習(xí) 課,坪山第二小學(xué) 莊海波,1 文具店,0.018,0.023,0.018,0.023,0.08,0.06,0.0110,0.5,0.0110,0.1,0.5,0.110 0.150 0.0160 0.01100 0.0012000,練習(xí)一,1,5,0.6,1,2,2 小數(shù)點(diǎn)搬家,小數(shù)：3.15,小數(shù)點(diǎn)向右移動一位：,31.5,小數(shù)點(diǎn)向右移動兩位：,315.,小數(shù)點(diǎn)向右移動三位：,3150.,小數(shù)點(diǎn)向右移1位，這個數(shù)擴(kuò)大10倍,小數(shù)點(diǎn)向右移2位，這個數(shù)擴(kuò)大100倍,小數(shù)點(diǎn)向右移3位，這個數(shù)擴(kuò)大1000倍,小數(shù)點(diǎn)向右移1位，這個數(shù)擴(kuò)大10倍 小數(shù)點(diǎn)向右移2位，這個數(shù)擴(kuò)大10

2、0倍 小數(shù)點(diǎn)向右移3位，這個數(shù)擴(kuò)大1000倍 （1.212.0）1.21012 （1.2 120.0）1.2100120 （1.2 1200.0）1.210001200,小數(shù)點(diǎn)向左移1位，這個數(shù)縮小10倍 小數(shù)點(diǎn)向左移2位，這個數(shù)縮小100倍 小數(shù)點(diǎn)向左移3位，這個數(shù)縮小1000倍,（1.20.12）1.210 0.12 （1.2 0.012）1.21000.012 （1.2 0.0012）1.210000.0012,12.5,125,1250,3,30,300,0.98,9.8,98,20.4,204,2040,2.48,0.248,0.0248,0.12,0.012,0.0012,0.06

3、,0.006,0.0006,42.5,4.25,0.425,32.510= 1.43100= 1.81000= 32.510= 1.43100= 1.81000=,算一算,325,143,1800,3.25,0.0143,0.0018,3 街 心 廣 場,53 50.3 0.53 0.050.3,乘數(shù)有多少個小數(shù)位，積就有多少個小數(shù)位,15,1.5,1.5,0.015,0,1,1,1,1,2,2,2,0,2,1,3,0.12,0.26,0.026,2 下面的積是幾位小數(shù)位，填在括號里 2.14= （ ） 30.112.3= （ ） 0.250.01= （ ） 70.256= （ ） 1.221

4、= （ ） 6.5410.1= （ ） 110.01= （ ） 8740.213= （ ）,1,3,4,3,1,4,2,3,4 包 裝,5 爬行最慢的動物,4.80.05,豎式計算一,1 看作整數(shù),2 豎式計算,3 算出乘數(shù)的小數(shù)位,4 點(diǎn)上積的小數(shù)點(diǎn),方法：,注意： 1 將位數(shù)多的數(shù)放在上面（方便計算） 2 在乘法，小數(shù)點(diǎn)不用對齊 3 豎式是要從右邊對齊,豎式計算二,1.950,練習(xí)題 豎式計算,0.362.3= 3.21.5= 0.254.4= 0.0071.8,6 手拉手,簡便計算,abc=(ac) b,1.251.890.8=(1.250.8) 1.89,ac+bc=(a+b) c,1.85.1+8.25.1=(1.8+8.2) 5.1,ac-bc=(a-b) c,10.85.1-0.85.1=(10.8-0.8) 5.1,2.50.9990.4,（2.50.4）0.999,10.999,0.999,0.861.258,0.86（1.258）,0.8610,8.6,簡便計算,9. 90.99. 90.1,簡便計算,（0.90.1）9.9,19.9,9.9,（0.80.08）12.5,0.812.50.0812.5,101,11