如何简便运算下列两道题：（1）20

1）20012001x2002-20022002x2001
= （2001x10000+2001）x 2002 - (2002x10000+2002)x2001
= 2001x10000x2002+2001x2002- 2002x10000x2001-2002x2001
=0
2 ) 19931993x1994-19941994x1993
= (1993x10000+1993)x1994-(1994x10000+1994)x1993
=1993x1994x10000+1993x1994-1994x1993x10000-1994x1993
=0