Quetta
Quetta is a unit prefix in the metric system denoting multiplication by 10^{30} or 1000000000000000000000000000000 (one nonillion). It is represented by the letter Q. It was approved by the 27th meeting of the General Conference on Weights and Measures in 2022. Since its introduction, it has been the largest prefix in the SI prefix system. Its inverse counterpart is quecto.
The letter "Q" was chosen as it was one of two remaining letters not in use for other unit prefixes and it was not commonly used for other units. The name "quetta" was selected as it began with that letter, and because of its slight resemblance to the Greek word δέκα deka 'ten' (quetta represents 1000^{10}).
Inclusion
The CGPM adopted the prefix quetta in addition to ronna, ronto, and quecto in their 27th meeting.
Usage examples
Prefix  Base 10  Decimal  English word  Adoption  

Name  Symbol  Short scale  Long scale  
quetta  Q  10^{30}  1000000000000000000000000000000  nonillion  quintillion  2022  
ronna  R  10^{27}  1000000000000000000000000000  octillion  quadrilliard  2022  
yotta  Y  10^{24}  1000000000000000000000000  septillion  quadrillion  1991  
zetta  Z  10^{21}  1000000000000000000000  sextillion  trilliard  1991  
exa  E  10^{18}  1000000000000000000  quintillion  trillion  1975  
peta  P  10^{15}  1000000000000000  quadrillion  billiard  1975  
tera  T  10^{12}  1000000000000  trillion  billion  1947  
giga  G  10^{9}  1000000000  billion  milliard  1947  
mega  M  10^{6}  1000000  million  1873  
kilo  k  10^{3}  1000  thousand  1795  
hecto  h  10^{2}  100  hundred  1795  
deca  da  10^{1}  10  ten  1795  
10^{0}  1  one  –  
deci  d  10^{−1}  0.1  tenth  1795  
centi  c  10^{−2}  0.01  hundredth  1795  
milli  m  10^{−3}  0.001  thousandth  1795  
micro  μ  10^{−6}  0.000001  millionth  1873  
nano  n  10^{−9}  0.000000001  billionth  milliardth  1960  
pico  p  10^{−12}  0.000000000001  trillionth  billionth  1960  
femto  f  10^{−15}  0.000000000000001  quadrillionth  billiardth  1964  
atto  a  10^{−18}  0.000000000000000001  quintillionth  trillionth  1964  
zepto  z  10^{−21}  0.000000000000000000001  sextillionth  trilliardth  1991  
yocto  y  10^{−24}  0.000000000000000000000001  septillionth  quadrillionth  1991  
ronto  r  10^{−27}  0.000000000000000000000000001  octillionth  quadrilliardth  2022  
quecto  q  10^{−30}  0.000000000000000000000000000001  nonillionth  quintillionth  2022  
