Répondre :
(1000 -1)(1000 + 1) = 10^6 - 1 = 999 999
999 999² = (10^6 - 1)² = 10^12 - 2.10^6 + 1
100 0000² = (10^5)² = 10^10
999 999² = (10^6 - 1)² = 10^12 - 2.10^6 + 1
100 0000² = (10^5)² = 10^10