Solution:
We have First odd number is 1
Last odd number is 49
a = 1 an or I = 49 ,common difference d= 2.
an = a+(n-1)d
=1+(n-1)2 = 49
=1+2n-2 =49
=2n-1 =49
=2n=49+1
=2n=50
n=25
sn=n/2(1+49)
=25/2(1+49)
=25/2* 50
25 *25 = 625
therefore sum of all odd numbers between 0 to 50 is 625.
