0.9999+0.999+0.99+0.9 该如何简算?

问题描述:

0.9999+0.999+0.99+0.9 该如何简算?

加上0.0001+0.001+0.01+0。1 然后减去

0.9999+0.999+0.99+0.9
=1-0.0001+1-0.001+1-0.01+1-0.1
=4-0.1111
=3.8889

0.9999×10000+0.999×10000+0.99×10000+0.9×10000
=9999+9990+9900+9000
=38889

0.9999+0.999+0.99+0.9
=1*4-((1-0.9999)+(1-0.999)+(1-0.99)+(1-0.9))
=4-(0.0001+0.001+0.01+0.1)
=4-0.1111
=3.8889

原式=1*4-(0.1+0.01.0.001+0.0001)
=4-0.1111
=3.8889