Scientists already had a need to discuss such large and small numbers but lacked the official terminology to do it with. So, many of them made up their own terms, like “hella” and “bronto,” but this can get pretty confusing. When those terms started to hit the mainstream media, the powers-that-be at SI decided to make some tweaks. They couldn’t just use the terms that were already in casual use, however, as metric prefixes are always shortened to be only the first letter (K for kilo, for example). Measurement terms starting with H and B were already spoken for, so that’s why hella and bronto couldn’t be considered candidates.
“The only letters that were not used for other units or other symbols were R and Q,” said Richard Brown, head of metrology at the U.K.’s National Physical Laboratory, according to a ScienceAlert article. Brown helped to draft the proposal for the new numbers. “The middle of the words are very, very loosely based on the Greek and Latin for 9 and 10.” Also part of the naming conventions: Smaller measurement prefixes always end in O, and larger ones finish off with an A.
Brown added that additional larger and smaller numbers should not be necessary for 20 to 25 more years, when it’s likely that science will continue to break barriers, once again.