Sum of odd numbers from 1 to 100?

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