0.9+0.99+0.999+0.9999+0.99999
=1-0.1+1-0.01+1-0.001+1-0.0001+1-0.00001
=5-(0.1+0.01+0.001+0.0001+0.00001)
=5-0.11111
=4,8888998989898*99999999÷101010÷11111111简便，求您了98989898*99999999÷101010÷11111111=98989898÷101010*99999999÷11111111=(98989800+98)÷101010*9=98989800÷101010*9+98÷101010*9=980*9+882÷101010=8820+441/50505=8820又441/50505