Editing 2319: Large Number Formats

{{comic
| number    = 2319
| date      = June 12, 2020
| title     = Large Number Formats
| image     = large number formats-2.png
| titletext = 10^13.4024: A person who has come back to numbers after a journey deep into some random theoretical field
}}

==Explanation==
{Incomplete}. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This comic shows what the way you write large numbers says about you. Different people use different methods to express large numbers. And this comic claims it can tell something about you based on the way you format large numbers. In this way, the comic is similar in idea to [[977: Map Projections]], where it was your choice of map projections that could tell something about you.

See the [[#Table of types|table]] below for each of the 10 different ways to express large numbers, plus the 11th mentioned in the title text.

The number used as an example is the [https://www.wolframalpha.com/input/?i=Distance+to+Jupiter+in+inches approximate distance] from the planet {{w|Earth}} to the planet {{w|Jupiter}} as of the release day of the comic on June 12th 2020, in {{w|inch|inches}} (1 inch = 2.54 cm).

Two days after the release of the comic the following text could be found on [https://theskylive.com/jupiter-info Jupiter info] on [https://theskylive.com/ The Sky Live].
:The distance of Jupiter from Earth is currently 640,084,108 kilometers, equivalent to 4.278698 Astronomical Units. Light takes 35 minutes and 35.0908 seconds to travel from Jupiter and arrive on Earth.

64,008,410,800,000 cm / 2.54 inches/cm = 25,200,161,732,283 inches - much less than the number used in the comic. But Jupiter's distance to Earth changes quite quickly, and was decreasing at the time of the release of the comic. 

According to a graph of the distance as a function of time on The Sky Live, the distance on the release day was 643,1 million km. This will give 25,3<sup>13</sup> which the used number will round to. 

The used number 25,259,974,097,204 is equivalent to 641,6 million km. On June 13th the distance is given as 641,7 million km in the graph on The Sky Live, very close to the number used. As this was the day after the release of this comic, it seems like [[Randall]] used a different distance than the exact one for the release day. He may have also used an average for June which would be 642 million km based on the average of the distance on June and July 1st.

==Table of types==
{| class="wikitable"
|-
! Number
! Type of person
! Notes
|-
| 25,259,974,097,204
| Normal Person
| This is the full number, 25259974097204, written out in the normal fashion, with commas to indicate powers of 1000. Although writing out the number in full is indeed a common action for normal people, the specific comma convention depicted here is only considered normal in the Anglo-Saxon world; conventions for writing large numbers in full vary considerably across cultures. For example, in countries where the comma is used as a {{w|decimal separator}} (including Europe outside the UK), one would write the number as 25.259.974.097.204 (or 25'259'974'097'204 in Switzerland, or 25 259 974 097 204 in Poland, France and Estonia). Under the {{w|Indian numbering system}}, this number would be written as 25,25,997,40,97,204. 
|-
| 25 Trillion
| Normal Person
| This is the number, rounded to trillions in the normal fashion.
|-
| 25 Billion
| Old British Person
| In current English usage, across the Anglophonic world with some hold-outs, an n-illion means 10^(3n+3) as per the {{w|short scale}} system popularised by American influence in international trade, so a trillion means 10^12, as above. However, older British English use had an n-illion meaning 10^(6n) (i.e. the simpler calculation of ''million^n''), so a billion meant 10^12. The change stems from a 1974 commitment by Harold Wilson, the Prime Minister of the UK at the time, to change from the {{w|long scale}} (previously often described as the British system) to the short one for all official purposes.

Though not instantly widely adopted for common usage, the mid-'70s could therefore be considered the key turning point between when an older or younger British person learns (as the change filters through the system at various stages of education) what their "Billion"s and "Trillion"s are supposed to represent.

As well as 'traditionalist' British use, the long scale is widely used in the non-Anglophone world, in local language versions, though while the British system tended to infill n-and-a-half powers of the million with the term "thousand n-illion", the suffix "-illi''ard''", or equivalent, is often used for the thousands multiple directly atop the respective "-illion" point.
|-
|2.526x10<sup>13</sup>
|Scientist
|This number is formatted in {{w|scientific notation}}, using the exponent 10<sup>13</sup>.
|-
| 2.525997x10<sup>13</sup>
| Scientist trying to avoid rounding up
| Using as many decimal places as necessary until hitting a digit (0-4) that results in rounding down, even if it goes against the common scientific practice of reporting the correct amount of "significant figures". [[:File:large number formats.png|A previous version of the comic]] had a typo (the number was ''2.5997x10<sup>13</sup>''), but Randall updated the comic.
|-
| 2.526e13 or
2.526*10^13
| Software developer 
| The first example is how the number would be expressed as a floating point number in scientific notation in [https://rosettacode.org/wiki/Literals/Floating_point most common programming languages]. The second example is a technically correct way of expressing the same thing in some programming languages in which exponentiation is indicated by the ^ operator. However writing it that way instead of the first way could be considered quirky, as it is written as an instruction to the computer to calculate the product of a number with 10 raised to power 13, instead of just writing the number (although in many situations  the compiler or preprocessor would detect this and solve it correctly, making it functionally identical to the first case). A software developer might write it that way if they are a novice who is not familiar with the first notation, or they could simply have an personal preference that considers the second version easier to read. Perhaps an additional joke for the second version is that it is the standard scientific notation with the x for multiplication and superscript for raising to a power replaced with the notation used in many programming languages of * and ^, i.e., a software developer writing down a number in scientific notation, not necessarily while writing a program, would by habit write a * for multiplication and a ^ for exponentiation. 
|-
| 25,259,973,541,888
| Software developer who forgot about floats
| The two most common computer {{w|Floating-point arithmetic|floating-point}} formats are the IEEE 754 {{w|Single-precision floating-point format|single-precision}} and {{w|Double-precision floating-point format|double-precision}} representations.  These are ''binary'' floating-point formats, representing numbers as the quantity ''a'' &times; 2<sup>''e''</sup>, for some fractional number ''a'' and exponent ''e''.  Both the values ''a'' and ''e'' have a fixed size in bits, and therefore a finite range.  In single-precision, ''a'' and ''e'' have (effectively) 24 and 8 bits, respectively, while in double precision the effective sizes are 53 and 11 bits.

Fully representing the number 25,259,974,097,204 (in any format) requires at least 45 bits.  Therefore this number cannot be represented exactly as a single-precision float.  The closest possible representations are 0.717931628 &times; 2<sup>45</sup> and 0.717931688 &times; 2<sup>45</sup>; these work out to 25,259,973,541,888 and 25,259,975,639,040, respectively.  Of these, the one ending in 888 is considerably closer to the original, so is chosen due to {{w|rounding}}.  (Naturally these numbers are represented internally in binary, not decimal; the actual representations, in {{w|hexadecimal}}, are <tt>0.b7ca5e</tt> &times; 2<sup><tt></tt>2d</sup> and <tt>0.b7ca5f</tt> &times; 2<sup><tt></tt>2d</sup>.)

In many programming languages, the keyword to request a single-precision floating-point variable is <tt>float</tt>, while the keyword to request double-precision is <tt>double</tt>.  It is an easy mistake to make to forget about the limited precision available with type <tt>float</tt>, especially since its name sounds like what you want for "floating point".  (Had the programmer remembered to use type <tt>double</tt>, the number 25,259,974,097,204 could have been represented exactly (still in hexadecimal), as <tt>0.b7ca5e43c9a000</tt> &times; 2<sup><tt></tt>2d</sup>.)
|-
| 10<sup>13</sup>
| Astronomer
| For extremely large distances, astronomers typically only care about orders of magnitude, e.g. whether a number is 10<sup>13</sup>, as opposed to 10<sup>12</sup> or 10<sup>14</sup>. Randall often jokes about the lack of precision needed by astronomers, such as in [[2205: Types of Approximation]] where the astronomer-cosmologist is equally willing to make pi equal to one, or ten. The original number is rounded to the nearest power of ten.
|-
| {∅,{∅},{∅,{∅}},{∅,{∅},{...
| Set theorist
| In {{w|Zermelo–Fraenkel set theory}}, the natural numbers are defined recursively by letting 0 = ∅ (the {{w|empty set}}), and ''n'' + 1 = ''n'' ∪ {''n''}. So, every natural number ''n'' is the set of all natural numbers less than ''n'', and since 0 is defined as the empty set, all numbers are nested sets of empty sets. Note that writing out the full number in this fashion would take more than its square in number of characters; that is to say, if each character took up one square inch, this "number" would not fit on a square piece of paper whose edge reached to Jupiter.
|-
| 1,262,998,704,860 score and four
| Abraham Lincoln
| In the {{W|Gettysburg Address}}, Lincoln speaks the number "87" as "four score and seven" ("score" meaning "20"). Base-20 or {{w|vigesimal}} numeral systems are or have been used in pre-Columbian-American, African and many other cultures. In French it is used only for higher numbers (e.g. 92 = quatre-vingt-douze). In English it can appear in certain archaic and classic contexts, such as the King James translation of the Bible ("threescore years and ten"  to be the life expectancy of a human according to Psalm 90:10).  In these cases, a number is written in "score" (multiples of 20) plus a remainder. In this case 1,262,998,704,860 * 20 + 4 yields the exact number.
|-
| 10^13.4024 ''(title text)''
| A person who has come back to numbers after a journey deep into some random theoretical field
| In some fields of mathematics, especially those dealing with very {{w|large numbers}}, numbers are sometimes represented by raising ten (or some other convenient base) to an oddly precise power, to facilitate comparison of their magnitudes without filling up pages upon pages of digits.  An example of this is {{w|Skewes's number}}, which is formally calculated to be ''e''<sup>''e''<sup>''e''<sup>79</sup></sup></sup>, but is more commonly approximated as 10<sup>10<sup>10<sup>34</sup></sup></sup>. 13.4024 is a rounded version of the {{w|common logarithm}} of 25,259,974,097,204 (log<sub>10</sub> 25,259,974,097,204 = 13.4024329009); thus, this "format" is still mathematically correct, but uncommon. However, only by using many more digits will the result get close enough to be rounded to the original number 10^13.40243290087302 = 25,259,974,097,203.5, which would round up to the correct number. This number 10^13.4024 = 25,258,060,548,319.6 deviating almost 2 billion from the correct number
|}

==Transcript==
:[A panel only with text. At the top there is four lines of explanatory text. Below that are 2 columns with 5 rows of number formats. Each numerical format is in red, with black text explaining the format below it.]

:<big>What the way you write large numbers says about you</big>
:(Using the approximate current distance to Jupiter in inches as an example)

:<span style="color:#ba0000">25,259,974,097,204</span>
:Normal person

:<span style="color:#ba0000">25 trillion</span>
:Normal person

:<span style="color:#ba0000">25 billion</span>
:Old British person

:<span style="color:#ba0000">2.526x10<sup>13</sup></span>
:Scientist

:<span style="color:#ba0000">2.525997x10<sup>13</sup></span>
:Scientist trying to avoid rounding up

:<span style="color:#ba0000">2.526e13 or 2.526*10^13</span>
:Software developer

:<span style="color:#ba0000">25,259,973,541,888</span>
:Software developer who forgot about floats

:<span style="color:#ba0000">10<sup>13</sup></span>
:Astronomer

:<span style="color:#ba0000">{∅,{∅},{∅,{∅}},{∅,{∅},{...</span>
:Set theorist

:<span style="color:#ba0000">1,262,998,704,860 score and four</span>
:Abraham Lincoln

{{comic discussion}}

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