1003 X 997 = (1000+....) (.....+.....) = .............................................
105 X 95 = (.......+.....) (........-.....) = .......................................
999 X 1001 = (...........) (............) = ....................................
491 X509 = ...........................................................................
1003 × 997 = (1000 + 3) (1000 - 3)
= 1000² - 3²
= 999 991
105 × 95 = (100 + 5) (100 - 5)
= 100² - 5²
= 9975
999 × 1001 = (1000 - 1) (1000 + 1)
= 1000² - 1²
= 999 999
491 × 509 = (500 - 9) (500 + 9)
= 500² - 9²
= 249919