201² = (200 + 1)² = 200² + 2*200*1 + 1² = 40000 + 400 + 1 = 40401,
72² = (70 + 2)² = 70² + 2*70*2 + 2² = 4900 + 280 + 4 = 5184,
302² = (300 + 2)² = 300² + 2*300*2 + 2² = 90000 + 1200 + 4 = 91204,
89² = (90 - 1)² = 90² - 2*90*1 + 1² = 8100 - 180 + 1 = 7921
