急求简便计算(四年级下册)28*225-2*225 -6*225 17*23-23*7 72*125 99*38+38 18*12+18*38 102*56

问题描述:

急求简便计算(四年级下册)28*225-2*225 -6*225 17*23-23*7 72*125 99*38+38 18*12+18*38 102*56

28*225-2*225 -6*225
=(28-2-6)×225
=4500
17*23-23*7
=(17-7)×23
=10×23
=230
72*125
=72×100+72×25
=7200+1800
=9000
99*38+38
=(99+1)×38
=100×38
=3800
18*12+18*38
=18×(12+38)
=18×50
=900
102*56=100×56+2×56
=5600+112
=5712

28*225-2*225 -6*225 =(28-2-6)*225=4500
17*23-23*7 =(17-7)*23=230
72*125 =8*125*9=9000
99*38+38=(99+1)*38=3800
18*12+18*38=18*(12+38)=18*40=720
102*56=(100+2)*56=5600+112=5720

28*225-2*225-6*225
=225×(28-2-6)
=225×20
=4500
17*23-23*7
=23×(17-7)
=23×10
=230
72*125
=9×8×125
=9000
99*38+38
=38×(99+1)
=38×100
=3800
18*12+18*38
=18×(12+38)
=900
102*56
=100×56+2×56
=5600+112
=5712

1. 225×(28-2)=225×26=225×(20+6)=225×20+225×6=4500+1350=5850
2. 23×(17-7)=23×10=230
3. 9×8×125=9×1000=9000
4. 38×(99+1)=3800
5. 18×(12+38)=18×50=900
6. (100+2)×56=5600+112=5712