Preferred number

These subdivisions ensure that when some arbitrary value is replaced with the nearest preferred number, the maximum relative error will be on the order of 40%, 20%, 10%, 5%, etc.

Commonly produced dimensions for other types of electrical components are either chosen from the Renard series instead or are defined in relevant product standards (for example wires).

This series is used to define the scales for graphs and for instruments that display in a two-dimensional form with a graticule, such as oscilloscopes.

The 1⁄4–1⁄2–1 series (... 0.1 0.25 0.5 1 2.5 5 10 ...) is also used by currencies derived from the former Dutch gulden (Aruban florin, Netherlands Antillean gulden, Surinamese dollar), some Middle Eastern currencies (Iraqi and Jordanian dinars, Lebanese pound, Syrian pound), and the Seychellois rupee.

However, newer notes introduced in Lebanon and Syria due to inflation follow the standard 1–2–5 series instead.

In the 1970s the National Bureau of Standards (NBS) defined a set of convenient numbers to ease metrication in the United States.

This system of metric values was described as 1–2–5 series in reverse, with assigned preferences for those numbers which are multiples of 5, 2, and 1 (plus their powers of 10), excluding linear dimensions above 100 mm.

[5] For example, a set of nominal center frequencies for use in audio tests and audio test equipment is: When dimensioning computer components, the powers of two are frequently used as preferred numbers: Where a finer grading is needed, additional preferred numbers are obtained by multiplying a power of two with a small odd integer: In computer graphics, widths and heights of raster images are preferred to be multiples of 16, as many compression algorithms (JPEG, MPEG) divide color images into square blocks of that size.

Standard metric paper sizes use the square root of two (√2) as factors between neighbouring dimensions rounded to the nearest mm (Lichtenberg series, ISO 216).

Measured film speeds are rounded to the nearest preferred number from a modified Renard series including 100, 125, 160, 200, 250, 320, 400, 500, 640, 800...

In some countries, consumer-protection laws restrict the number of different prepackaged sizes in which certain products can be sold, in order to make it easier for consumers to compare prices.

Adjacent package sizes in these lists differ typically by factors 2⁄3 or 3⁄4, in some cases even 1⁄2, 4⁄5, or some other ratio of two small integers.