Question

Find the sum of all three-digits natural numbers which are divisible by 13.

Answer 1

All three-digit numbers which are divisible by 13 are 104, 117, 130, 143,.…… 938.

This is an AP in which a = 104, d = (117 - 104) = 13 and l = 938

Let the number of terms be n

Then T_n = 938

Hence, the required sum is 37674.