Find the sum of first n odd natural numbers.
a = 1, d = 2
Sum of first n odd numbers, Sn = 
[2a + (n – 1) d]
= 
[2(1) + (n – 1) 2]
= n [1 + n – 1]
= n2
12
Find the sum of first n odd natural numbers.
a = 1, d = 2
Sum of first n odd numbers, Sn = [2a + (n – 1) d]
= [2(1) + (n – 1) 2]
= n [1 + n – 1]
= n2