12 + 1 + 112 + 2 + 212 +...+ 4912 + 50.

12 + 1 + 112 + 2 + 212 +...+ 4912 + 50.

12 + 1 + 112 + 212 +...+ 4912 + 50, = (1 + 2 +...+ 50) × 2 - 50 + 12 × 50, = (1 + 50) × 50 은 2 × 2 - 50 + 25, = 2550 - 50 + 25, = 2525.