Recently, I was getting a lot of free time and there wasn’t any interesting questions to solve on Stack Overflow as well. I was searching for something to code when I bumped into ProjectEuler.net. It has lot of interesting questions which can be solved in any language of our choice. I remember starting to solve these questions before but I had stopped after answering couple of them. Let’s see how far I can solve this time.

**Multiples of 3 and 5**

**Problem 1**

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000

List all the numbers completely divisible by 3 or 5 and sum them. A number is given as completely divisible when the modulus operand gives the remainder as 0.

x <- 1:999 sum(x[x %% 3 == 0 | x %% 5 == 0]) # [1] 233168