四年级下册数学简便运算

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,*,简便运算,乘法分配律：,(a,+,b)c =a c,+,b c,a,c +b c =(a,+,b)c,(a,b)c =a c,b c,a c,b c =(a,b)c,9 37+9 63,2,1,=,333+567,=,900,想,:4,和,25,相乘可凑成,4,25,=,500+100,=,600,9 37+9 63,想,:37,和,63,都与,9,相乘,37,和,63,相加可凑成,=,9,=,9,100,=,900,(,20,+4),25,=,600,=,2425,(,20,+4),25,整百数,整百数,=,20 +,25,37+63,（,）,3537+6537,=（35+65）37,=,10037,=,3700,12425,-,2524,=,(,124,-,24,),X,25,=,100,x,25,=,2500,8582+8215,52892,=（85+15）82,=,10082,=,8200,=（52）289,=,10289,=,2890,32,（,200+3,）,3829+38,=32200+323,=6400+96,=6496,=3829+381,=38,（,29+1,）,=3830,=1140,（12525）4,75299+75,=（254）125,=100125,=12500,=,75299+751,=,75,（,299+1,）,=75300,=22500,计算：,（,4,+,8,）,125,25,（,20,+,4,）,45,7,+,55,7,8,27,+,8,73,103 32,99 32,=,(,100,+,3,),32,=,100 32,+,332,1,2,=,3200,+,96,=,3296,=,(,100,-,1,),32,=,100 32,-,132,=,3200,-,32,=,3168,9911,329101,=（100-1）11,=10011-111,=1100-11,=1089,=329,（,100+1,）,=329100+3291,=32900+329,=33229,做一做：,9923,88102,=（100-1）23,=10023-123,=2300-23,=2277,=88,（,100+2,）,=88100+882,=8800+176,=8976,12588,（125+17）8,=125811,=100011,=11000,=125（80+8）=12580+125 8 =10000+1000 =11000,方法二：,=1258+178,=1000+136,=1136,102X99,100X99+2,102X（100-1）,102X100-102,100X99-99,99X99+99X3,（100+2）X99,102X100+102,已经用了多少块地砖？,每块地砖,12,元，准备了,1800,元够不够？,4、,8X12+8X7,=,8,X,（,12,+,7,）,=,8,X,19,=,152,（,块）,12,X,（,12X15,）,=2160,（,元）,2160,1800,答：准备了,1800,元不够。,