Question

几个数学简便算法

用简便方法计算
1.25X0.32

0.56X2.5

14.28÷0.7X2.56

1.57X6.4+3.6X1.57

10÷0.1X9.05-26

10.2X9.8

能简便的简便不能简便的列出来用托式计算

Answer 1

1.25X0.32=5/4*0.4*0.8=0.5*0.8=0.4
0.56X2.5=0.14*4*2.5=0.14*10=1.4
14.28÷0.7X2.56=2.04*7/0.7*2.56=20.4*2.56=20*2.56+0.4*2.56=51.2+1.24=52.44
1.57X6.4+3.6X1.57=1.57*(6.4+3.6)=1.57*10=15.7
10÷0.1X9.05-26=10*10*9.05-26=905-26=879
10.2X9.8=(10+0.2)*(10-0.2)=10^2-0.2^2=100-0.04=99.96

Answer 2

乘法分配：999*3=(1000-1)*3=3000-3=2997
加法分配：9+6+1=9+1+6=10+6=16
提取公因式：9+90+900=9（1+10+100）=999

Answer 3

1 1.25X0.32=1.25X8X0.04=10X0.04=0.4
2 0.56X2.5=2.5X4X0.14=1.4
3 14.28÷0.7X2.56=0