1003×999=
Using the following identity: (x+a)(x+b)=x2+(a+b)x+ab
⇒1003×999=[1000+(3)][000+(−1)]
=10002+[(3)+(−1)].1000+(3)(−1) [Using the identity (x+a)(x+b)=x2+(a+b)x+ab]
=1000000+(2)(1000)+(−3)
=1000000+2000+(−3)
=1001997
Therefore, the result is 1001997.