1. 0.2x18+5分之1x83-百分之20 2. 63.8x32x0.125x2.5 怎么简算？

1. 0.2x18+5分之1x83-百分之20
=0.2×18+0.2×83-0.2
=0.2×(18+83-1)
=0.2×100
=20

2. 63.8x32x0.125x2.5
=63.8×(8×0.125)×(4×2.5)
=63.8×1×10
=638

3. 0.25x0.25x......x0.25共有2008个0.25x4x4x......x4
=(0.25×4)×(0.25×4)×(0.25×4)×...×(0.25×4) (共2008对0.25×4 的乘积)
=1×1×1×...×1
=1

1、0.2X18+1/5X83-20%
=0.2X18+0.2X83-0.2
=0.2X(18+83-1)
=0.2X100
=20
2、63.8X32X(125/1000)X(25/10)
=63.8X32X(1/8)X(5/2)
=63.8X32x(5/16)
=63.8x10
=638

1、0.2X18+1/5X83-20%=0.2X18+0.2X83-0.2=0.2X(18+83-1)=0.2X100=20
2、63.8X32X(125/1000)X(25/10)=63.8X32X(1/8)X(5/2)=63.8X32x(5/16)=63.8x10=638
3、原式=2.5×4×2.5×4×2.5×4×2.5×4×2.5×4×2.5×4×2.5×4×2.5×4×2.5×4×......=1

1.. 0.2x18+0.2x83+0.2x1=0.2x102=20.4
2.. 63.8x(4x8)x0.125x2.5=63.8x((8x0.125)x(4x2.5)=63.8x1x10=638
3.. 记住，0.25和4相乘等于1

提示：125x8=1000 25x4=100 用交换 结合 或分配律简算
请问第三题是（28个0.25）x（28个0.4）吗？

见图

不会

0.125x2.5x8的简算~

0.125x8x2.5
=1x2.5
=2.5

(0.2x20+1.5)+(0.2x19+1.5)+(0.2x18+1.5)+...+(0.2x11+1.5)
=0.2×（20+11）×10/2+1.5×10
=31+15
=46