724 x 999 = 723 276
= 724 x ( 1 000 - 1 ) =
= 724 x 1 000 - 724 x 1 =
= 724 000 - 724 = 723 276
_______________________
380 x 999 = 379 620
= 380 x ( 1 000 - 1 ) =
= 380 x 1 000 - 380 x 1 =
= 380 000 - 380 =
= 379 620
_______________________
405 x 999 = 404 595
= 405 x ( 1 000 - 1 ) =
= 405 x 1 000 - 405 x 1 =
= 405 000 - 405 =
= 404 595
