Series would be: 1,3,5......99
Here, a=1, d = 3-1 = 2, l = 99
l = a+(n-1)d
99 = 1+(n-1)2
98 = 2n-2
2n = 100
n = 50
Sum would be Sn = n/2 (a+l)
50/2 (1+99)
25(100) = 2500
So, your answer is 2500
