Find the sum of all odd numbers between
(i) 0 and 50
(ii) 100 and 200
a = 1, l = 49, n = 25
S25= [a + l]
= [1 + 49]
= (50) = 625
a = 101, l = 199, n = 50
S50= [a + l]
= 25 (101 + 199)
= 25 (300) = 7500