用简便方法计算:0.9+0.99+…+0.999999999.
问题描述:
用简便方法计算:0.9+0.99+…+0.999999999.
答
0.9+0.99+…+0.999999999
=(1-0.1)+(1-0.01)+…+(1-0.000000001)
=9-0.111111111
=8.888888889