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Peta (//) is a decimal unit prefix in the metric system denoting multiplication by 1015 (1000000000000000). It was adopted as an SI prefix in the International System of Units in 1975, and has the symbol P.
Peta is derived from the Greek πέντε, meaning "five". It denotes the fifth power of 1000 (10005). It is similar to the prefix penta ("five"), but without the letter n (on the analogy of the prefix tera [from the Greek for "monster"] for 10004 looking like tetra- ["four"] with a letter missing).
- 1 petametre = 1015 metres
- 1 petasecond = 1015 seconds (31.7 million years)
- 1 petahertz = 1015 cycle per second. Visible light is around 0.5 PHz.
- 1 petabyte = 1015 bytes
- the mass–energy equivalence is 89.9 PJ/kg
- 1 light-year = 9.461 Pm
- Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.
- "Resolution 10 of the 15th meeting of the CGPM (1975)". International Bureau of Weights and Measures. Retrieved 2012-04-18.