1999*1998*1998-1998-19991999
=1999*(2000-2)*(2000-2)-1998-1999*10000-1999
=1999*(2000*2000-2*2*2000+2*2)-1999*10000-3997
=1999*3920004-1999*10000-3997
=1999*3910004-4000+2
=2000*3910004-3910004-4000+2
=7820008000-3906002
=7960021999
1999*1998*1998-1998-19991999
=1999*(2000-2)*(2000-2)-1998-1999*10000-1999
=1999*(2000*2000-2*2*2000+2*2)-1999*10000-3997
=1999*3920004-1999*10000-3997
=1999*3910004-4000+2
=2000*3910004-3910004-4000+2
=7820008000-3906002
=7960021999