小数乘法简便计算练习.ppt

,整数乘法运算定律推广到小数,计算下面各题:,25 95 4,=25495 =10095 =9500,25 32,=2548 =1008 =800,4 48+6 48,=（4+6）48 =1048 =4800,=（100+2）56 =10056+256 =5600+112 =5712,102 56,1、应用乘法运算定律填空。,（1） 7.80.81.25 =( ) （2）（8+10）12.5 = + （3） 1.74.2+1.75.8 = ( + ),7.8,0.8,1.25,8,12.5,10,12.5,1.7,4.2,5.8,4.21.69（ ）（ ） 2.50.770.4（ ）（ ）（ ） 6.13.6+3.93.6（ + ）（ ）,1.69,4.2,2.5,0.4,0.77,6.1,3.9,3.6,不计算，直接把上下两排得数相等的算式用线连起来。 712 8( 54) (24+36) 5 (85)4 245+365 127,把左右相等的式子用线连起来。,用简便方法计算下面各题。,0.1258.8,=0.12581.1 =11.1 =1.1,0.0340.50.6,=0.034（0.50.6） =0.0340.3 =0.0102,1020.45,=（100+2）0.45 =1000.45+20.45 =45+0.9 =45.9,用简便方法计算下面各题。,=1.5100+1.52 =150+3 =153,2.330.54,=2.33（0.54） =2.332 =4.66,=（1.2 0.8）2.5 =0.42.5 =1,1.5102,1.22.5 - 0.82.5,0.251.250.48,=（0.254）（1.258） =110 =10,能用简便方法的就用简便方法，并说一说运用了哪些运算定律。,（1）1.251780,0.68101,3.652.83.657.2,5.4199,=1.258017 =10017 =1700,=（2.8+7.2）3.65 =103.65 =36.5,=0.68（100+1） =0.68100+0.681 =68+0.68 =68.68,=5.4（200-1） =5.4200-5.41 =1080-5.4 =1074.6,下面各题怎样简便就怎样算。 0.2799 3.89.9+3.80.1 320.125 1.382.54,=0.27（100-1） =0.27100 - 0.27 =27 - 0.27 =26.73,=4（80.125） =40.1 =0.4,=3.8（9.9+0.1） =3.810 =38,=1.38（2.54） =1.3810 =13.8,用简便方法计算。,0.258.54 =0.2548.5 =18.5 =8.5 2.41.02 =2.4（10.02） =2.412.40.02 =2.40.048 =2.448,1.288.60.728.6 =（1.280.72）8.6 =28.6 =17.2 12.50.960.8 =12.50.80.96 =100.96 =9.6,用简便方法计算下面各题。,1.22.5 - 0.82.5,1.5102,0.0340.50.6,0.251.250.48,课堂练习： 500.130.2 1.5102 0.32.50.4 2.6699 3.175.6+3.174.4,0.78100.5 1.250.70.8 1.22.5+0.82.5 1.252.30.8 1032.4,用简便方法计算下面各题。,0.0340.50.6 1020.45 4.80.25 2.330.54 1.5105 1.22.5+0.82.5,0.5446+5.45.4 0.251.2532, 0.5 0. 034 0.6, 102 0.45,2、用简便方法计算（说说我是怎样想的， 理由是什么,计算时应注意什么）。, 3.89.9,用简便算法计算下面各题。,0.78100.5 1.5105 8.4998.4,用简便方法算下面各题。 2.524 0.25320.125 3.799 6.81016.8,=2.546 =106 =60,=(0.254)(80.125) =11 =1,=3.71003.7 =3703.7 =366.3,=6.8100 =680,=2.5(46),=0.25(48)0.125,=3.7(1001),=6.8(1011),用简便方法计算下面各题。,1020.45 0.0340.50.6 16.7101 0.641253 5.6998 1.22.5+0.82.5 4.80.25 2.330.54 0.8124 8.81.25 1.5105 （0.64+0.64+0.64+0.64）2.5,课堂作业,用简便方法计算下面各题： 4.561.54.441.5 0.1257.4980 3.1499 （0.250.125）8,0.32.50.4 0.78101 1.22.50.82.5 9.825,18.76-3.47-0.53 3.2+0.8-3.2+0.8,7.810.1 363.4+366.6 0.22.5,怎样简便就怎样