Nines (notation) facts for kids
Have you ever heard someone say something is "three nines fine"? This is a special way to talk about how pure something is, especially when it's super, super pure!
"Nines" simply means counting how many nines are in a percentage or a decimal. For example, if something is 99% pure, it has "two nines." If it's 99.9% pure, it has "three nines." It's a quick way to show how close something is to being 100% pure.
Sometimes, you might hear things like "three nines five." This means it's 99.95% pure. If something were perfectly 100% pure, it would have an endless number of nines!
Super Pure Metals
When we talk about very valuable metals like gold, silver, and platinum, their exact purity is really important. The "nines" system helps us understand just how pure they are.
This system is based on something called millesimal fineness. This means how many parts per thousand of the metal are pure. For example, if a metal is 900 fine, it means 900 parts out of 1000 are pure metal. That's 90% pure.
Here's how "nines" are used for precious metals:
- If a metal is 90% pure (900 fine), it's called one nine or one nine fine.
- If it's 99% pure (990 fine), it's called two nines fine.
- If it's 99.9% pure (999 fine), it's called three nines fine.
This "nines" system is like a special scale for measuring how incredibly pure these valuable metals are. When a percentage ends in a 5, like 99.95% pure (which is 999.5 fine), it's often called "three nines five," or sometimes just "3N5."
| Percent purity | Millesimal fineness | Nines |
|---|---|---|
| 90% | 900 | 1 nine |
| 99% | 990 | 2 nines |
| 99.9% | 999 | 3 nines |
| 99.95% | 999.5 | 3 nines 5 |
| 99.97% | 999.7 | 3.5 nines |
| 99.99% | 999.9 | 4 nines |
| 99.995% | 999.95 | 4 nines 5 |
| 99.999% | 999.99 | 5 nines |
| 99.9999% | 999.999 | 6 nines |
Pure Gases
The "nines" scale is also used to describe how pure bottled gases are. Gas purity tells us how much of the gas is the main gas, and how little of it is other unwanted gases (impurities). A higher purity means fewer other gases.
Gases with higher purity are usually better quality and cost more money. The purity of a gas is often shown with the letter "N" followed by the number of nines. For example:
- An N2.0 gas is 99% pure. This means 1% of it is other gases.
- An N6.0 gas is 99.9999% pure (six nines). This gas has only 1 part per million (ppm) of impurities, which is very, very little!
So, whether it's precious metals or special gases, "nines" help us understand just how pure something truly is!
See also
- List of unusual units of measurement
- Parts-per notation
- 0.999...
