请写出解题过程:999×998998999-998×999999998

问题描述:

请写出解题过程:
999×998998999-998×999999998

=999 x (998998998+1) - 998 x (999999999 -1)
=(999 x 998 x 1001001 +999)-(998 x 999 x1001001 -998)
=998 + 999
=1997