The same basic sizes are increasingly being used internationally. That’s nice, it makes mutual communication a lot easier. We indicate larger and smaller variants of the basic sizes with a prefix, a short addition before the actual basic size. We all know prefixes in indications such as kilometers, centimeters, millimeters. Kilo = one thousand, centi = the hundredth of a cubit, milli = the thousandth of a part. There are many more. The (international) SI system specifies exactly which ones there are, which names and symbols we use for them.
The SI system
With the many international trade contacts, it is nice if the same indications for length measurements, volume measurements or weights are used internationally. The SI System ( Système International d’unités , or: the International System of Units ), which was introduced on October 11, 1960, stipulates which basic sizes are used internationally. In addition, agreements have been made about names, numbers, spelling of numbers and the prefixes in the metric system.
Metric system
The metric system dates from 1799, when the French, led by Napoleon, had power in Europe. To bring unity to the many different measurement systems used in all countries and regions, a new system was devised. The new system was based on basic measurements for length (the meter ), weight (the gram ) and volume (the liter ). In addition, larger and smaller sizes were devised by means of prefixes. Each smaller or larger size differed from the previous one by a factor of 10. In short, not only the sizes were updated, but the mutual relationships were also standardized.
The first prefixes
In this example we assume length. The new standard for this became the meter .
- 10 meters was called a decameter, deca is derived from Latin and means: 10
- 100 meters was called a hectometer, where hecto stands for 100
- 1000 meters was called a kilometer, where kilo stands for 1000
Smaller than the meter is also possible:
- 0.1 meter became a decimeter, deci = the tenth.
- 0.01 meters became a centimeter, centi = the hundredth
- 0.001 meters became a millimeter, milli = the thousandth
In the same way, with the same prefixes, the measurements for weight (grams) and volume (liters) were indicated: kilograms, centilitres, etc. The measurements were chosen in such a way that there was a mutual relationship. One cubic decimeter has the same volume as one liter.
New prefixes
It soon became apparent that many more prefixes were needed. Much smaller and also much greater lengths, weights, etc. are conceivable. To prevent each country from coming up with its own system, coordination had to be done. Agreements have been made about this in the SI system. The new system gives new prefixes to powers of 1000, because otherwise the total of prefixes would be much too large. This means that measurements such as centimeters, decimeters and hectometers are actually ignored, but they can still be used.
The new list of prefixes in the SI system
In the list of prefixes below you will see:
- The power of numbers. For example: 103 = 10 x 10 x 10 = 1000
- The prefix used
- The symbol of this prefix
- The name of the multiplication number
- The number written out in full
|
Power |
Prefix |
Symbol |
Name number |
Number |
|
10 24 |
yotta |
Y |
quadrillion |
1 000 000 000 000 000 000 000 000 |
|
10 21 |
zetta |
Z |
trillion |
1 000 000 000 000 000 000 000 |
|
10 18 |
exa |
E |
trillion |
1 000 000 000 000 000 000 |
|
10 15 |
peta |
P |
quadrillion |
1 000 000 000 000 000 |
|
10 12 |
tera |
T |
trillion |
1 000 000 000 000 |
|
10 9 |
huge |
G |
billion |
1 000 000 000 |
|
10 6 |
mega |
M |
million |
1 million |
|
10 3 |
kilos |
k |
thousand |
1 000 |
|
10 0 |
1 |
|||
|
10 −3 |
milli |
m |
thousandth |
0.001 |
|
10 −6 |
micro |
µ |
millionth |
0.000 001 |
|
10 −9 |
nano |
n |
billionth |
0.000 000 001 |
|
10−12 _ |
pico |
p |
trillionth |
0.000 000 000 001 |
|
10 −15 |
femto |
f |
quadrillionth |
0.000 000 000 000 001 |
|
10−18 _ |
atto |
a |
trillionth |
0.000 000 000 000 000 001 |
|
10 −21 |
zepto |
z |
trillionth |
0.000 000 000 000 000 000 001 |
|
10 −24 |
yocto |
y |
quadrillionth |
0.000 000 000 000 000 000 000 001 |
Prefixes disappeared?
You can see that the list above is missing some old well-known prefixes:
- hecto (hundred)
- deca (ten)
- deci (tenth)
- centi (hundredth)
These prefixes are officially no longer part of the SI standards. However, these designations are so widely known and used that they can still be applied in practice.
Spelling
Please note: the SI system prescribes whether symbols should be capitalized or not. In the diagram above you will also see, for example, a Z and a z, with very different values. This also means that, for example, you are not allowed to write km as Km, even if that is at the beginning of a sentence. For example, the following sentence is correct:
km is the symbol of kilometer.
read more
- Fahrenheit, Celsius and Kelvin
- Measuring with meters is knowing
- Measuring, but with what?
- The International System of Units