...} series can be defined as binary. That means that the R10 series can be formulated as R10 ≈ bR3 = , generating just 9 values of R10, just because of the kind of periodicity. This way rounding is eliminated, as the 3 values of the first period are repeated multiplied by 2. The usual cons however is that the thousand product of such multiplication is shifted slightly: Instead of decadic 1000, the binary 1024 appears, as classics in IT. The pro is that the characteristics is now fully valid, that whatever value multiplied by 2 is also member of the series, any rounding effectively eliminated. The multiplication by 2 is possible in R10 too, to get another members, but the long fractioned numbers complicate the R10 accuracy. See also Preferred numbers Preferred metric sizes 1-2-5 series E series (preferred numbers) Logarithm Decibel Neper Phon Nominal Pipe Size (NPS) Geometric progression References Further reading (Replaced: ) Numbers Industrial design Logarithmic scales of measurement