How much is it?

Asking the price: Bao nhiêu tiền?

You already know bao nhiêu from counting. Add tiền (money) and you have the price question. The thing comes first and the question follows it: Cái này bao nhiêu tiền? In a quán people often shorten it to Bao nhiêu tiền? or just Bao nhiêu?

Prices are counted in nghìn

The currency is the đồng, and everyday prices run in thousands: a coffee is 25 000, a bowl of phở 40 000. That is why the word you hear most is nghìn, a thousand. People usually drop đồng, and often nghìn too – hai mươi lăm is enough.

Một bát phở bốn mươi nghìn đồng.A bowl of phở is forty thousand đồng.

đắt means expensive and rẻ means cheap. Both come after the thing, with rất in front of them for very: Cái này rất đắt. The word for the price itself is giá, so you can also ask Giá bao nhiêu?

Asking for the bill: tính tiền

tính is to count, so tính tiền is to count the money – the Vietnamese way of asking for the bill. Two forms are equally common: Cho tôi tính tiền. and Tính tiền cho tôi. After that you trả tiền, you pay.