The last time this was done was 1991 when we added two larger prefixes – zetta [Z] (1 with 21 zeroes) and yotta [Y] (1 with 24 zeroes) and two smaller prefixes – zepto [z] (21 zeroes to the right of the decimal point) and yocto [y] (24 zeroes).
Now, the 27th General Conference on Weights and Measures introduced four new prefixes to the International System of Units, or metric system. On the “larger” scale, the first new prefix is ronto [R] (1 with 27 zeroes) and quecto [Q] (1 with 30 zeroes). On the “smaller” scale, the two new prefixes are ronna [r] (27 zeroes to the right of the decimal point) and quetta [q] (27 zeroes.)
"Most people are familiar with prefixes like milli- as in milligram," Richard Brown, head of metrology at the U.K.'s National Physical Laboratory who proposed the four new prefixes, told The Associated Press. "But these [new additions] are prefixes for the biggest and smallest levels ever measured."
On the larger scale, we can now state the Earth’s mass as 6 ronnagrams rather than 6,000 yottagrams. The sun is 2,000 quettagrams rather than 2,000,000,000 yottagrams. On the smaller scale, now an electron’s mass is said to be 1 rontogram rather than 0.001 yoctograms.
"It was high time. [We] need new words as things expand," Brown said. "In just a few decades, the world has become a very different place."