20022003×20032002-20022002×20032003
=20022002×20032002+1×20032002
-20022002×20032003
=20022002×(20032002-20032003)+
20032002
=20032002-20022002
=10000
20022003×20032002-20022002×20032003
=20022002×20032002+20032002-(20022002×20032002+20022002)
=20022002×20032002+20032002-20022002×20032002-20022002
=20032002-20022002
=10000