1、小 数 乘 法 复 习,北京版五年级数学上册,教学目标,本节课我们主要来复习小数乘法,同学们要能够掌握有关小数乘法的相关内容,可以熟练应用小数乘法解决实际问题。,0.018,0.023,0.018,0.023,0.08,0.06,0.0110,0.5,0.0110,0.1,0.5,0.1100.1500.01600.011000.0012000,1,5,0.6,1,2,小数:3.15,小数点向右移动一位:,31.5,小数点向右移动两位:,315.,小数点向右移动三位:,3150.,小数点向右移1位,这个数扩大10倍,小数点向右移2位,这个数扩大100倍,小数点向右移3位,这个数扩大1000倍,
2、小数点向右移1位,这个数扩大10倍小数点向右移2位,这个数扩大100倍小数点向右移3位,这个数扩大1000倍(1.212.0)1.21012(1.2 120.0)1.2100120(1.2 1200.0)1.210001200,小数点向左移1位,这个数缩小10倍小数点向左移2位,这个数缩小100倍小数点向左移3位,这个数缩小1000倍,(1.20.12)1.210 0.12 (1.2 0.012)1.21000.012(1.2 0.0012)1.210000.0012,32.510=1.43100=1.81000=32.510=1.43100=1.81000=,算一算,325,143,1800
3、,3.25,0.0143,0.0018,5350.30.530.050.3,乘数有多少个小数位,积就有多少个小数位,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,下面的积是几位小数位,填在括号里。2.14= ( ) 30.112.3= ( )0.250.01= ( ) 70.256= ( )1.221= ( ) 6.5410.1= ( )110.01= ( ) 8740.213= ( ),1,3,4,3,1,4,2,3,4.80.05,竖式计算一,1.看作整数,2.竖式计算,3.算出乘数的小数位,4.点上积的小数点,方法:,注
4、意:1.将位数多的数放在上面(方便计算)2.在小数乘法中,小数点不用对齐3.竖式是要从右边对齐,竖式计算二,1.950,练习题竖式计算,0.362.3= 3.21.5= 0.254.4=0.0071.8,简便计算,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,简便计算,9. 90.99. 90.1,简便计算,(0.90.1)9.9,19.9,9.9,(0.80.08)12.5,0.812.50.0812.5,101,11,简便计算,2.50.8640.1121.2589.19249.19149.98.80.18.8(10.8)12.5(0.40.04)25,本课小结,本节课我们主要复习了哪些内容?同桌之间互相讨论一下!,