0.9+0.99+0.999+0.9999+.0.99...9(有N个9)=?
问题描述:
0.9+0.99+0.999+0.9999+.0.99...9(有N个9)=?
答
=1-0.1+1-0.01+1-0.001+...=n-0.111111111(n个)
0.9+0.99+0.999+0.9999+.0.99...9(有N个9)=?
=1-0.1+1-0.01+1-0.001+...=n-0.111111111(n个)