Np-q≤k≤np+p
300*0.9-0.1≤k≤300*0.9+0.9
269.9≤k≤270.9
k=270
120² = (12×10)² = 12² × 10² = 144 ×100 = 14400
80² = (8 ×10)² = 8² × 10² = 64 ×100 = 6400
110² = (11×10)² = 11² ×10² = 121×100= 12100
170² = (17×10)² = 17² ×10²= 289×100=28900
250² = (25×10)² = 25² × 10² =625×100=62500