Ve so: the lottery ticket somebody offers you every day

Somebody will offer you a lottery ticket within an hour of sitting down at a Vietnamese pavement cafe. It will happen again at lunch, and again in the evening, and the person offering will usually be old, or on crutches, or both.

Ve so is the most visible informal trade in the country, and understanding the arithmetic behind it changes how the interaction feels.

How does it work?

A state system with a street-level distribution network, run province by province rather than nationally.

Each ticket carries a date and one province's draw, which is why a seller fans out a dozen and why yesterday's are worthless. Numbers are pre-printed, so you pick a ticket rather than picking numbers.

Who is selling them?

The people with the fewest other options are the ones selling. Sellers are overwhelmingly elderly, disabled, or migrants from poorer provinces; they buy tickets from an agent at a discount and carry the risk of anything unsold.

At about 1,000 dong a ticket, a seller moves a hundred tickets to earn 100,000 — under four US dollars. That is the whole economics of the walk, and the reason the same person is on the same corner from morning until the draw.

Children selling tickets is a real and widely criticised part of the trade. Buying from one keeps it going, and the honest response is to decline politely and buy from an adult instead.

Should you buy one?

Buy one if you feel like it. A ticket costs 10,000 dong, under half a dollar. No scam attaches to it: the price is printed, the seller cannot alter it, and nobody follows you.

Treat it as a purchase rather than as charity. Handing over money without taking the ticket is well meant and reads as pity, and most sellers would rather sell you the thing they are carrying. If you would like to give more, buy several.

How do you say no?

A small shake of the head, a raised hand, or a quiet "khong, cam on" — no, thank you. The language guide has the phrase. Nobody argues and nobody follows.

What lands badly is the pretence that the person is not there, which is the default foreign reaction and the one Vietnamese people do not use. A refusal is normal and gets a nod; being invisible does not.

Expect several approaches an hour in a busy district and one or two a day in a quiet one. Sellers work the same tables in rotation, so the same person may come back — a second no is as unremarkable as the first.

What happens at four o'clock?

The results go up on boards outside every lottery agent. Phones come out at the pavement cafes and a brief flurry of ticket-checking runs down the street. The coffee shop guide describes the setting it happens in.

Small prizes are paid on the spot by agents and sellers, including the common one for matching the last two digits. Anything large needs the ticket itself, identification and a trip to the provincial lottery company: a bureaucratic day rather than a scene from a film.

Where does it fit the bigger picture?

Ve so sits alongside the street vendors with a shoulder yoke: two versions of an informal economy that is visible, legal and thin-margined. Both reward understanding more than photographing, and both respond well when you treat them as trade rather than as scenery.

One last thing worth knowing. The state lotteries fund provincial budgets, and the southern provinces in particular publish what they raise — which is why a trade that looks informal at street level is run by a company with an office, a licence and an audited set of accounts.