1 + 2 + 1 = 4, 1 + 2 + 3 + 2 + 1 = 9, 1 + 2 + 3 + 4 + 3 + 2 + 1 = 16, 계산 (1) 1 + 2 + 3 +...+ 99 + 100 =?

1 + 2 + 1 = 4, 1 + 2 + 3 + 2 + 1 = 9, 1 + 2 + 3 + 4 + 3 + 2 + 1 = 16, 계산 (1) 1 + 2 + 3 +...+ 99 + 100 =?

1 + 2 + 1 = 4, - > 2 ^ 2 = 4
1 + 2 + 3 + 2 + 1 = 9, - > 3 ^ 2 = 9
1 + 2 + 3 + 4 + 3 + 2 + 1 = 16; - > 4 ^ 2 = 16
1 + 2 + 3 +... + n - 1 + n + 1 +... + 2 + 1, - > n ^ 2
1 + 2 + 3 + 4 +... + 100 + 99 +... + 2 + 1 = 100 ^ 2 = 10000