Question

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.

C

#include <stdio.h>

int main(int argc, char **argv)
{
    int sum = 0;
    for (int i = 0; i < 1000; i++) {
        if (i % 3 == 0 || i % 5 == 0) {
            sum += i;
        }
    }
    printf("%d\n", sum);
    return 0;
}

$ gcc -march=native -Ofast -std=c11 -o natural natural.c
$ time ./natural
real   0m0.001s
user   0m0.000s
sys    0m0.001s

Clojure

#!/usr/bin/env clojure
(defn multiple? [n]
  (or (= (rem n 3) 0) (= (rem n 5) 0)))

(println (reduce + (filter multiple? (range 1000))))

$ time clojure natural.clj
real   0m0.900s
user   0m1.699s
sys    0m0.113s

Go

package main

import "fmt"

func main() {
    sum := 0
    for i := 0; i < 1000; i++ {
        if i%3 == 0 || i%5 == 0 {
            sum += i
        }
    }
    fmt.Println(sum)
}

$ go build -o natural natural.go
$ time ./natural
real   0m0.001s
user   0m0.000s
sys    0m0.001s

Haskell

main ::  IO ()
main = print $ sum [n | n <- [1..999], or [(n `mod` 3 == 0), (n `mod` 5 == 0)]]

$ ghc -O2 -o natural natural.hs
$ time ./natural
real   0m0.002s
user   0m0.000s
sys    0m0.002s

JavaScript

let s = 0
for (var i = 1; i < 1000; i++) {
  if (i % 3 === 0 || i % 5 === 0) {
    s += i
  }
}
console.log(s)

$ time node --use-strict natural.js
real   0m0.052s
user   0m0.044s
sys    0m0.009s

Python

#!/usr/bin/env python
print(sum(i for i in range(1000) if (i % 3 == 0) or (i % 5 == 0)))

$ time python3 natural.py
real   0m0.016s
user   0m0.016s
sys    0m0.000s

Ruby

#!/usr/bin/env ruby
sum = 0
1000.times do |i|
  if i % 3 == 0 or i % 5 == 0
    sum += i
  end
end
puts sum

$ time ruby natural.rb
real   0m0.039s
user   0m0.038s
sys    0m0.000s

Rust

fn main() {
    let result: u64 = (1..1000).filter(|x| x % 3 == 0 || x % 5 == 0).sum();
    println!("{}", result);
}

$ rustc -C target-cpu=native -C opt-level=3 -o natural natural.rs
$ time ./natural
real   0m0.001s
user   0m0.000s
sys    0m0.001s

Scheme

(display
  (reduce + 0
          (filter
            (lambda (n)
              (or (= (remainder n 3) 0) (= (remainder n 5) 0)))
            (iota 1000))))
(newline)

$ time mit-scheme --quiet < natural.scm
real   0m0.040s
user   0m0.024s
sys    0m0.019s