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Comment by howlgarnish | Hacker News Reader

Here's a completely legal and fully specified address in Singapore:

Or if you're sending international mail:

  SINGAPORE 238801

Explanation: Singapore is a city-state with no divisions for states, counties etc, and every single house and building has its own unique 6-digit postcode, so that number is all you need to receive mail or locate an address. Of course, in practice people usually put in the regular road address as well for redundancy, but it's not really necessary.

  Ion Orchard
  2 Orchard Turn
  SINGAPORE 238801

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Ireland seems to achieved the same thing (tiny addresses being accepted) in a far more casual fashion just on account of being both very small and sparse.

https://www.irishpost.com/news/eight-times-irish-postmen-ama...

I would imagine other locations like New Zealand or Iceland have the same phenomena. We adopted EirCodes (Irish Postcodes) purely so people felt they had something to type in to online forms when ordering -- sometimes programmers insisted on post code when we didn't have any in Ireland. Before this I would just use IRL00 by default.

Yeah, most of the addresses where I grew up had no postcode of any description. Remember sticking forms of "munster", "mun" or "mun001" in there (the ones that validated it by UK Post code logic were the worst).

Later I moved to Dublin which had postcodes but they were more postal districts. So my postcode was "Dublin 8", which again was rejected by a lot of validators.

now we have eircodes so my postcode at that same address is d08 xxxx. We're getting on some sites the US style autofill of address based on Eircode as a result. but not everywhere's used to it. Just Eat, the largest takeaway ordering site goes sets my address to <house number>, <Street name>, <County Dublin>, but if I leave that as is, some local takeaways, including some very near to me see that as County Dublin as opposed to Dublin City and cancel the order thinking I'm out of delivery range, so I need to correct the final field to Dublin 8 anyway.

Somewhat similarly in the Netherlands, while the full address is generally used, the postcode (say 1012CK)* and the number (say 17) is sufficient to uniquely identify a place in the country.

* this is a random place I found on google maps. Don't send them mail.

Apparently the Radisson Blu Hotel in Amsterdam.

The US kind of/sort of has a similar thing with extended zip codes. From what I understand, the postal service usually assigns an extended zip code for each building they deliver to. If you’re at a single family residence, then it’s equivalent to the Singaporean example above (though it’s possible the postal service will still reject a letter addressed to just an extended zip code!).

I'm not sure what extended zip codes are as I'm only aware of the zip codes like 90210 which cover a large area. But here in the NL a lot of online shopping for example don't even ask you for the street name, just the post code (4 digits + 2 letters) and of course your house number. You type in the post code and the street name gets filled in, leaving you with just the house number to enter.

You'll see the US's extended ZIP codes referred to as Zip+4, as they have nine digits instead of the usual five. So, 90210-1234 refers to a specific Delivery Sector and Delivery Segment within Beverly Hills. The segment can be a particular building or even just one floor of a building. Or, it can refer to all the buildings on one side of the street. It's up to the post office.

I used to work with a guy who would send mail to his mom at:

> Ma

> <postcode>

> Scotland

Supposedly it worked because his local postman knew there was only one woman on the route with a son who would be sending mail from the US. Which didn’t sound like a very reliable method, but he claimed it never failed.

In the UK the postcode would be often applied to only one street (or a part of a street). This means in practice you get small villages with a postcode that covers 2 houses for example. The local postman could likely know the residents well enough in that case.

Average number of properties per post code is 15 (max about 100), so a lot smaller than a route. And in rural area the routes are often kept to the same small group of staff for years.

SW1A 1AA is sufficient for a letter to Buckingham Palace. You should probably include the name of the person.

It's not unusual. The university residence halls I lived in had postcodes unique to the building, and my first employer in London has several postcodes for several nearby buildings.

I have sent something to "{name} Somewhere near the brewery {town}" and it reached the destination. They will often try and deliver these kind of incomplete addresses.

Many postal systems have a "difficult cases" department whose job is to try to decipher otherwise undeliverable addresses.

How does that work with a population of 6 million?

Apparently there’s no more than 999,999 unique residences?

You are assuming all post codes have the same length by any chance? :)

In Singapore they're always 6 digits.

Singapore is a city-state on an island that is ~40x20 km in size. If you divided that rectangle evenly to a million plots, you'd end up squares that have ~30m sides. And that's before you consider that the island is not square, and that there are roads, airports, parks and things like that.

No, there are not anywhere near a million unique buildings. Instead, there are ~9000 high-rises.

1,000,000 if the code 000000 counts

95% of Singapore's population lives in apartment buildings of some kind, which pack tens if not hundreds of households into each post code.

Is there a check digit?

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