The odd numbers between 0 and 50 are 1,3,5,7,9…49
Therefore, it can be observed that these odd numbers are in an A.P.
a = 1, d = 2, l = 49
l = a + (n − 1)d
49 = 1 + (n − 1)2
48 = 2(n − 1)
n − 1 = 24
n = 25
Sn = \(\frac{n}{2}\)(a + l)
S25 = \(\frac{25}{2}\)(1 + 49)
= \(\frac{25\times50}{2}\)
= 625
