Parts-per notation Uno IUPAP's "uno" proposal

| Coefficient | Parts_per_example | Uno_equiv_ | Symbol_form | Value_of_quantity |
|---|---|---|---|---|
| 10 −2 | 2% | 2 centiuno | 2 cU | 2×10 −2 |
| 10 −3 | 2 ‰ | 2 milliuno | 2 mU | 2×10 −3 |
| 10 −6 | 2 ppm | 2 microuno | 2 µU | 2×10 −6 |
| 10 −9 | 2 ppb | 2 nanouno | 2 nU | 2×10 −9 |
| 10 −12 | 2 ppt | 2 picouno | 2 pU | 2×10 −12 |