In Vietnamese, two consecutive numbers can come together to express approximate quantities, similar to “about”, “around” or “approximately” in English.
Basic usage
Place two consecutive numbers next to each other in ascending order.
Structure
number + (number + 1)
Examples
- ba bốn ngườithree or four people
- Họ sẽ mất sáu bảy ngày để thích nghi.It will take them six or seven days to adapt.
- Ông ấy khoảng bốn năm mươi tuổi.He’s about forty or fifty years old.
More advanced usages
Beside the basic usage with increment of one, there are several more advanced usages, which involve:
- Increment of more than one
- Decrement
- Non-numerical quantifiers, including quasi-numerical nouns
Naturally, the larger the number is, the less sense it makes to have an increment of only one. While increments of 10, 100, etc. can be easily formed by simply adding mươi/chục, trăm, etc. increments of as few as two or five are also possible. However, note that they are not applicable to all, but rather only to some specific numbers.
The table below is a non-exhaustive list of the more advanced usages.
| Category | Quantity | Meaning |
|---|---|---|
| Increment of five | mười mười lăm | 10–15 |
| mười lăm hai mươi | 15–20 | |
| Increment of two | năm bảy | 5–7 |
| mười tám hai mươi | 18–20 | |
| Decrement | năm ba | 3–5 (lit. 5–3) |
| Non-numerical quantifiers | một vài | 1–3 |
| vài ba | 2–3 | |
| Quasi-numerical nouns | đôi ba | 2–3 |
| dăm bảy | 5–7 | |
| dăm ba | 3–5 (lit. 5–3) | |
| mươi mười lăm | 10–15 | |
| mười tám đôi mươi | 18–20 |
Extra notes
The short forms of two-digit numbers sound exactly like consecutive one-digit numbers, which may leave room for multiple interpretations. For example, hai ba can mean either “two to three” or “twenty-three”. However, there is always context. Context will tell what the expected quantity is (below or above ten), which indicates the intended interpretation.