1000 ! .( 456 . 789789 - 789 . 456456 )
= 1000 ! x ( 456 x 789 x 1001 - 789 x 456 x 1001 )
= 1000 ! x 0 = 0
1000 ! .( 456 . 789789 - 789 . 456456 )
= 1000 ! x ( 456 x 789 x 1001 - 789 x 456 x 1001 )
= 1000 ! x 0 = 0
1000 ! . ( 456 . 789789 - 789 . 456456 )
= 1000 ! . ( 456 . 789 . 1001 - 789 . 456 . 1001 )
= 1000 ! . 0
= 0