Answer:
Femto is a prefix used in SI system for the multiple 10-15 and its symbol is f. In 1964, it was incorporated into to the International System of Units (SI). It comes from the Danish word femten, which implies fifteen.
Examples:
- The diameter of a proton is 1.66 femtometres.
- The HIV-1 virus has a mass of approximately 1 x 10-15 g or 1 fg.
