2005×2003 /2004
=（2004+1）×2003 /2004
=2004×2003 /2004+2003/2004
=2003又2003/2004
999+99+9+8/9*3+1/3
=999+99+9+8/3+1/3
=999+99+9+3
=999+1+99+1+9+1
=1110