bonjour
• 499999 = 500 000 - 1 = 5 x 10⁵ - 1
(499999)² = (5 x 10⁵ - 1)²
= (5 x 10⁵)² - 2 x 5 x 10⁵ + 1
= 5² x 10¹⁰ - 10 x 10⁵ + 1
= 25 x 10¹⁰ - 10⁶ + 1
• 999999 = 1 000 000 - 1
= 10⁶ - 1
on ajoute les deux nombres
(499999)² + 999999 = 25 x 10¹⁰ - 10⁶ + 1 + 10⁶ - 1
= 25 x 10¹⁰
