用简便方法计算下面各题28.4-6.9=21.5
发布网友
共3个回答
热心网友
436+98=436+100-2=536-2=534
32.8+5.6+7.2=32.8+7.2+3.6=40+3.6=43.6
28.4-6.9=28.4-(7-0.1)=28.4-7+0.1=21.4+0.1=22.4
11.2-4.7-5.3=11.2-(4.7+5.3)=11.2-10=1.2
125*24=125*4*6=500*6=3000
13.7*0.25*8=13.7*(0.25*8)=13.7*2=27.4
31.5/45==31.5/5/9=6.3/9=0.7
2.65*1.7+1.315*1.7=(2.65+1.35)*1.7=4*1.7=6.8
热心网友
28.4-6.9
=28.4-（7-0.1）
=28.4-7+0.1
=21.4+0.1
=21.5
热心网友
28.4-6.9
=（28.4-7）+0.1
=21.4+0.1
=21.5
