Project Euler solutions http://projecteuler.net/

euler-001.py

def check_number(num):         
    return (num % 3 == 0 or num % 5 == 0)     

def sum_it(upto):         
    sum = 0         

    for i in range(1, upto):         
        if check_number(i): sum += i         
    return sum         

print sum_it(1000)

euler-001.rb

puts (0...1000).select { |n| n % 3 == 0 || n % 5 == 0 }.inject(0) { |s,n| s += n }

euler001.erl

-module(euler001).
-export([sumnaturals/0]).

sumnaturals() ->
	lists:sum([A || A <- lists:seq(1,999), (A rem 3 =:= 0) or (A rem 5 =:= 0)]).