CAT Exam Model Paper 7 with solutions for free online practice

Let d be the common difference and a be the first term of AP The fifth term of the series will be a + 4d.
If a + 4d is divisible by d then a should also be divisible by d. Hence the cases are:
d = 1, a = 1,2, 3......16
d =2, a = 2, 4, 6......12
d = 3. a = 3, 6
d = 4, a = 4
So the answer is 16 + 6 + 2 + 1 =25.