We know that the sum of first \(n\) odd natural numbers is \(n^2\).
(i) \(49 = (7)^2\)
Therefore, \(49\) is the sum of first \(7\) odd natural numbers.
\(49 = 1 + 3 + 5 + 7 + 9 + 11 + 13\)
(ii) \(121 = (11)^2\)
Therefore, \(121\) is the sum of first \(11\) odd natural numbers.
\(121 = 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21\)