Two quick ways: 1) Google your address just using what you know. Usually Google Maps fills it in for you!2) Go to usps.com (if you're from the USA) and click the "find a zipcode" link in the top bar....
Go to any Search engine and type zip codes world wide or if you know the country name that country. An example is that for instance Canada doesn't use zip codes, we use Postal codes so be sure the...