Solution:

1, 3, 5, 7, 9 … 49 are the odd numbers between 0 and 50.

As a result, we can see that these odd numbers are in the form of A.P.

Hence,

The first term, a = 1

The common difference, d = 2

The last term, l = 49

Using the formula of the last term, we know,

l = a+(n−1) d

49 = 1+(n−1)2

48 = 2(n − 1)

n − 1 = 24

n = 25 = Number of terms

Using the formula of the sum of nth term, we know,

S_n = n/2(a +l)

S₂₅ = 25/2 (1+49)

= 25(50)/2

=(25)(25)

= 625