![]() For example, 12.5 ×10 −9 m can be read as "twelve-point-five nanometers" (10 −9 being nano) and written as 12.5 nm, while its scientific notation equivalent 1.25 ×10 −8 m would likely be read out as "one-point-two-five times ten-to-the-negative-eight meters".Įngineering notation, like scientific notation generally, can use the E-notation, such that 3.0 ×10 −9 can be written as 3.0E−9 or 3.0e−9. On the other hand, engineering notation allows the numbers to explicitly match their corresponding SI prefixes, which facilitates reading and oral communication. It is also common to state the precision explicitly, such as " 47 kΩ ± 5%"Īnother example: when the speed of light (exactly 299 792 458 m/s by the definition of the meter) is expressed as 3.00 ×10 8 m/s or 3.00 ×10 5 km/s then it is clear that it is between 299 500 km/s and 300 500 km/s, but when using 300 ×10 6 m/s, or 300 ×10 3 km/s, 300 000 km/s, or the unusual but short 300 Mm/s, this is not clear. In the previous example, 0.5 mm, 0.50 mm, or 0.500 mm would have been used to show uncertainty and significant figures. In some cases this may be suitable in others it may be impractical. This can be solved by changing the range of the coefficient in front of the power from the common 1–1000 to 0.001–1.0. Some graphical calculators (for example the fx-9860G) in the 2000s also support the display of some SI prefixes (f, p, n, µ, m, k, M, G, T, P, E) as suffixes in engineering mode.Ĭompared to normalized scientific notation, one disadvantage of using SI prefixes and engineering notation is that significant figures are not always readily apparent when the smallest significant digit or digits are 0. in the FX-501P/ FX-502P), where number display in engineering notation is available on demand by the single press of a ( INV) ENG button (instead of having to activate a dedicated display mode as on most other calculators), and subsequent button presses would shift the exponent and decimal point of the number displayed by ☓ in order to easily let results match a desired prefix. This can be seen as a precursor to a feature implemented on many Casio calculators since 1978/1979 (e.g. Between 19 the same exponent shift facility was also available on some Texas Instruments calculators of the pre- LCD era such as early SR-40, TI-30 and TI-45 model variants utilizing ( INV) EE↓ instead. In 1975, Commodore introduced a number of scientific calculators (like the SR4148/SR4148R and SR4190R ) providing a variable scientific notation, where pressing the EE↓ and EE↑ keys shifted the exponent and decimal point by ☑ in scientific notation. It was implemented as a dedicated display mode in addition to scientific notation. Dickinson the first calculator to support engineering notation displaying the power-of-ten exponent values was the HP-25 in 1975. An early implementation of engineering notation in form of range selection and number display with SI prefixes was introduced in the computerized HP 5360A frequency counter by Hewlett-Packard in 1969.
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