=(2006-1)×2005/2006+(1003-2)×1002/1003
=2006×2005/2006-1×2005/2006+1003×1002/1003-2×1002/1003
=2005-2005/2006+1002-2004/1003
=(2005+1002)-(2005/2006+4008/2006)
=3007-6013/2006
=3004+3-6013/2006
=3004+5/2006
=3004又2006分之5