2004x20032003-2002x20042004
=2004×10001×2003-2002×10001×2004
=2004×10001×(2003-2002)
=20042004,9,2004x20032003-2002x20042004
=2004×10001×2003-2002×10001×2004
=2004×10001×(2003-2002)
=20042004,3,2004x20032003-2002x20042004
=2002x20032003-2002x20042004+2x20032003
=2002x(20032003-20042004)+40064006
=40064006-2002x10001
=40064006-2002000-2002
=20044006-2002
=20042004,1,