For the first time in more than 30 years, new terms have been officially added to the International System of Units (SI). The four new prefixes – ronna, quetta, ronto and quecto – describe very large and very small numbers that until now didn’t have their own names.

SI uses seven base units of measurement, such as the meter, which can be modified with prefixes (such as kilo) to describe large or small amounts of these units, which makes it easier to understand and communicate. So 649,000,000 bytes becomes 649 megabytes, or 0.001 meters becomes 1 millimeter.

But these names can only count so far. For more extreme numbers that don’t get used as often, the usual shorthand is scientific notation, where the superscript number describes how many zeroes there are. So 10^{9}, for example, represents 1,000,000,000, or 10^{-6} is 0.000001. While these might look fine in a scientific paper, they’re awkward in everyday conversation or more casual texts.

As technology advances and extreme numbers become more routine, new prefixes are needed. In this case, the driver was data – currently the volume of data created and consumed worldwide is measured in zettabytes (10^{21}), and beyond that there’s only one more named unit – the yottabyte, or 10^{24}.

So, at the General Conference on Weights and Measures (CGPM) this past weekend, global representatives voted to introduce four new prefixes to the SI. The number 10^{27} is now officially known as ronna and 10^{30} is now quetta, while 10^{-27} is ronto and 10^{-30} is quecto. This is in keeping with naming conventions that use prefixes ending in “a” for large numbers and “o” for small ones.

According to Dr. Richard Brown, Head of Metrology at the UK National Physics Laboratory (NPL) and lead scientist on the proposal, these names were chosen because R and Q were the last two letters of the alphabet that weren’t used for other prefixes. This is the first time since 1991 that new prefixes have been added to the table.

While ronnabytes and quettabytes of data will probably be their first uses, as with any SI prefixes these new ones can be used for any and all SI units of measurement. For instance, Earth’s mass is estimated at around 1 ronnagram, and Jupiter’s is about 1 quettagram. At the other end of the scale, the mass of an electron is 1 rontogram, while 1 quectogram is the mass of one bit of data stored on a mobile phone.

As for everyday use, we now have some fun new words to really exaggerate things in stories down at the pub. The team describes the new words in the video below.