用简便方法计算999999+99999+9999+999+99+9怎样算才能简便呢(⊙o⊙)?

999999+99999+9999+999+99+9
= 1000000-1 + 100000 -1 + 10000 - 1 + 1000 -1 + 100-1 + 10-1
= 1111110 - 6
= 1111104