Without adding, find the sum:
(i) (1 + 3 + 5 + 7 + 9 + 11 + 13)
(ii) (1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19)
(iii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23)
(i) We know that,
Sum of first n odd numbers = n2
Applying this formula in the question, we get
(1 + 3 + 5 + 7 + 9 + 11 + 13) = (7)2
= 49
(ii) We know that,
Sum of first n odd numbers = n2
Applying this formula in the question, we get
(1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19) = (10)2
= 100
(iii) We know that,
Sum of first n odd numbers = n2
Applying this formula in the question, we get
(1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23) = (12)2
= 144