Does 2k4 Mean 2004 or 2400?

Date: 01/10/2004 at 22:30:09
From: Sean
Subject: Is 2k4 2004 or 2400?

On internet communities it is common to reduce figures using K as a 
shortcut, for example 2k instead of 2000.  I was always under the
impression that a number after the K, such as 2k4, meant 2400 and that
to get 2004 in this system you'd need to write 2k004.

However, it is common for 2k4 to stand for 2004 instead.  Which is
correct? Is 2K4 2004 or 2400?

Date: 01/11/2004 at 22:55:29
From: Doctor Peterson
Subject: Re: Is 2k4 2004 or 2400?

Hi, Sean.

Interesting question!  Here's my take on it.  This appears to be a
recently invented notation, so the community that invented it and uses
it gets to define it!  If they use 2k4 for 2004 (as I have seen that
they do), then that's what it means.

Mathematically, the closest standard notation to this is the metric 
system, where 2 km means 2 kilometers; people apply that without a
unit and use "2k" to mean "2 thousand".  But there is nothing in that 
system to allow putting a number after the "k"; if it meant anything, 
it would mean "2000 4's", or 8000!  I know of no notation in which 
concatenation implies addition rather than multiplication.  For that 
reason, I'd rather see "2k+4" used instead of 2k4; but since there is 
no other way to take it, there's nothing really bad about using the 
latter notation.

In any case, I don't see that 2k4 would mean 2400 (2.4k), or that 
adding extra zeros would make it mean 2004.  I do know that in some 
cultures a unit can be used as the decimal point, at least in 
speaking if not in writing, as for example one might read "$2.04" 
as "two dollars four"; in that case, what follows the unit ("four") 
is not necessarily the next decimal place, but the next standard unit 
(in this case cents).  Taking that approach, 2k4 would probably still 
mean "2 thousand [and] four [units]".  So I see no problem from that 
quarter.

Because this piqued my curiousity, I did a little research and found
that, although I wasn't aware of it, electrical engineers do use 2k4
for 2.4k (in certain specific contexts) for practical reasons:

    http://www.ibiblio.org/obp/electricCircuits/DC/DC_4.html 

  In recent years a new style of metric notation for electric
  quantities has emerged which seeks to avoid the use of the
  decimal point.  Since decimal points (".") are easily misread
  and/or "lost" due to poor print quality, quantities such as
  4.7 k may be mistaken for 47 k.  The new notation replaces the
  decimal point with the metric prefix character, so that "4.7 k"
  is printed instead as "4k7".  Our last figure from the prior
  example, "0.267 m", would be expressed in the new notation
  as "0m267".

More details are given here:

    http://www.nutsvolts.com/PDF_Files/circuit.pdf 

  ... Matters reached a historic peak in 1975 when the British
  Standards Institute (BSI) published — after a very long period
  of study and consultation — a list of recommendations
  concerning this subject. ... [T]hose relating to an
  international system of electronic component value notation
  were excellent, and were soon adopted by most of the world’s
  industrial nations, with the notable exception of the USA.

  This new notation system was, in effect, an improved and
  streamlined version of the existing SI-based system, and was
  thus quite easy to learn.  When its basic form was first
  specified, it was required to be designed as a simple
  easily printed code that indicates an electronic component’s
  value clearly, briefly, without ambiguity, and with a minimum
  loss of clarity if poorly printed.

  This last requirement immediately ruled out the use of decimal
  points in the new code system, and the requirement for brevity
  called for (1) the elimination of all superfluous information
  from the code, and (2) for sensible compression of the
  remaining data.

  Regarding point (1) in the ‘brevity’ requirement, note that
  in circuit diagrams, when indicating the value of a symbolic
  resistor, capacitor, or inductor, it is self-evident that the
  component’s value is expressed in basic units of ohms, Farads,
  or Henrys, and the new code’s design specification thus
  demanded the elimination of this superfluous ‘postscript’ data
  from the printed code when used in circuit diagrams (but not
  necessarily in normal printed text).

  Regarding point (2) in the ‘brevity’ requirement, this was to
  be aided by using a fixed three decade spacing between the
  decimal ‘multiplier’ units used to indicate a component’s
  value.
  ...
  Decimal points sometimes become so severely degraded during
  the printing process that they cease to have a final
  practical value. ... The important thing to note from the above
  is that decimal points often become severely degraded during
  the printing process and, in their 1975 report, the BSI
  recommended that, for component/parameter value notation
  purposes, the decimal point should no longer be used and should
  be replaced by the basic component/parameter multiplier symbol
  (such as V, k, n, µ, etc.) applicable to that value.  Thus, in
  this system, values such as 4.7V, 4.7kW, and 4700pF (= 0.0047µF
  or 4.7nF) become 4V7, 4k7, and 4n7.
  
  There are four major differences between the International and
  US Customary notation systems, and two of these are illustrated
  in Figure 9, which shows the multiplier symbols that are used
  in the International system; compare this diagram with that of
  Figure 8, and note that the International system uses the
  symbol R to indicate basic resistance units, and uses the
  symbol n to indicate ‘thousandths of a µF’ capacitance units.

  Of the remaining two differences, one is that — in circuit
  diagrams — the International system does not use basic
  component ‘type’ symbols (such as W, F, or L) as component
  postscript notations, and the other is that the International
  system used the component’s multiplier symbol in place of a
  decimal point in the actual component-value notation.

This is only now becoming common in America, which explains why I 
wasn't familiar with it despite past experience in electronics.  But 
the main point is that this system is not a standard practice in SI, 
but only something used in the electronics industry; it can't be 
expected to influence popular usage, and thus has no real bearing on 
the "2k4" issue, except to add more weight to the fact that using 2k4 
for 2004 is non-standard and can only be considered an idiom, not a 
natural extension of any ordinary usage.

This page deprecates the usage for the reason you give:

    http://www.mit.edu/people/klund/2k2.html 

  In engineering, the construction "2k4" is often used as an
  abbreviation for "2.4k", meaning "two thousand, four hundred"
  (2400).  This construction replaces the decimal point with an SI
  exponent abbreviation to save space.  Similarly, "2M2" would be
  an abbreviation for the number 2,200,000 and "3m3" would be an
  abbreviation for the fraction 0.0033.

  Unfortunately, some people use "2k4" as an abbreviation for the
  current year, 2004.  This usage is dead wrong.  We all got
  excited when we figured out that we could abbreviate the year
  2000 as "Y2k," but it's over now.  There is no longer a short
  and clever abbreviation for the current year: we're just going
  to have to write out all four digits.  "2k4" and "2k5" won't be
  here for centuries. 

  Some people argue that "2k4" can be pronounced "two thousand
  four," so it is an acceptable written abbreviation.  Eye sea
  they're point, butt its still knot correct.

  Please, help stamp out the incorrect use of 2k4!  And don't
  start using 2k5.  Think of the children.

I don't feel quite so strongly about it, but I have to agree: if this 
usage continues for very long, it will become very silly.  Once we get 
to 2k10, hopefully people will realize they are not saving anything 
by replacing a 0 with a k!  Until then, we just have to warn them that 
they will not always be understood when they use it.  But then, that 
is part of the charm of jargon, and may not dissuade those who like 
cryptic language!

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/