Names of large numbers

Naming very large numbers is relatively easy. There are two main ways of naming a number: scientific notation and naming by grouping. For example, the number 500,000,000,000,000,000,000 can be called 5 x 10²⁰ in scientific notation since there are 20 zeros behind the 5. If the number is named by grouping, it is five hundred quintillion (American) or 500 trillion (European).

When large numbers have many different decimals in them, such as 642 500 000 000, naming them with scientific notation is about the same, but with one difference. Still counting the number of numbers after the first number (in this case, after the 6 there are 11 numbers) you need to include the ones that are not zero in the formula, but after a decimal point. So 642 500 000 000 will be 6.425 x 10¹¹. When naming by grouping, each group is the name of the group. With the same number, it would be said to be 642 billion, 500 million (US) or 642 milliard, 500 million (Eur).

Some examples

Number	Scientific notation	Grouping
600 000 000 000 000 000 000 000 000	6 x 1026	600 septillion (quadrillion)
765 476 250 000 000	7.6547625 x 1014	765 trillion, 476 billion, 250 million
145 000	1.45 x 105	145 thousand

Forms of numbering

The American way or "Short form" for naming large numbers is different from the European way or "Long form" of naming large numbers. This is mainly because of American finance. Short form numbering is based on thousands and Long form is based on millions. Because of this, in Short form a billion is one thousand millions (10⁹) while in Long form it is one million millions (10¹²). The change in the United Kingdom to Short form numbering happened in 1974. Today, Short form is most commonly used in most English speaking countries.

Names for large numbers

Scientific notation	American name (Short Form)	Old European name (Long Form)	Old-British name	SI Symbol	Metric prefix
1	One	One	One
10	Ten	Ten	Ten	da	Deca-
100	Hundred	Hundred	Hundred	h	Hecto-
1000	Thousand	Thousand	Thousand	k	Kilo-
10000	Ten thousand	Ten thousand	Ten thousand	my (Now obsolete)	Myria- (Now obsolete)
100000	Hundred thousand	Hundred thousand	Hundred thousand
1000000	Million	Million	Million	M	Mega-
1000000000	Billion	Milliard	Thousand million	G	Giga-
1012	Trillion	Billion	Billion	T	Tera-
1015	Quadrillion	Billiard	Thousand billion	P	Peta-
1018	Quintillion	Trillion	Trillion	E	Exa-
1021	Sextillion	Trilliard	Thousand trillion	Z	Zetta-
1024	Septillion	Quadrillion	Quadrillion	Y	Yotta-
1027	Octillion	Quadrilliard	Thousand quadrillion	R	Ronna-
1030	Nonillion	Quintilion	Quintillion	Q	Quetta-
1033	Decillion	Quintilliard	Thousand quintillion
1036	Undecillion	Sextillion	Sextillion
1039	Duodecillion	Sextilliard	Thousand sextillion
1042	Tredecillion	Septillion	Septillion
1045	Quattuordecillion	Septilliard	Thousand septillion
1048	Quindecillion	Octillion	Octillion
1051	Sexdecillion	Octilliard	Thousand octillion
1054	Septendecillion	Nonillion	Nonillion
1057	Octodecillion	Nonilliard	Thousand nonillion
1060	Novemdecillion	Decillion	Decillion
1063	Vigintillion	Decilliard	Thousand decillion
1066	Unvigintillion	Undecillion	Undecillion
1069	Duovigintillion	Undecilliard	Thousand undecillion
1072	Trevigintillion	Duodecillion	Duodecillion
1075	Quattuorvigintillion	Duodecilliard	Thousand duodecillion
1078	Quinvigintillion	Tredecillion	Tredecillion
1081	Sexvigintillion	Tredecilliard	Thousand tredecillion
1084	Septenvigintillion	Quattuordecillion	Quattuordecillion
1087	Octovigintillion	Quattuordecilliard	Thousand quattuordecillion
1090	Novemvigintillion	Quindecillion	Quindecillion
1093	Trigintillion	Quindecilliard	Thousand quindecillion
1096	Untrigintillion	Sexdecillion	Sexdecillion
1099	Duotrigintillion	Sexdecilliard	Thousand sexdecillion
10100	Googol	Googol	Googol
10102	Tretrigintillion	Septendecillion	Septendecillion
10105	Quarttourtrigintillion	Septendecilliard	Thousand septedecillion
10108	Quintrigintillion	Octodecillion	Octodecillion
10111	Sextrigintillion	Octodecilliard	Thousand octodecillion
10114	Septemtrigintillion	Novemdecillion	Novemdecillion
10117	Octotrigintillion	Novemdecilliard	Thousand novemdecillion
10120	Novemtrigintillion	Vigintillion	Vigintillion
10123	Quadragintillion	Quinquagintilliard	.
10153	quinquagintillion
10303	Centillion	Quinquagintilliard
10^3003	millionillion
10^3000003	micrillion
10^10^9	nanillion
10^10^12	Picillion
10^10^33	mecillion
10^10^100	googolplex
10^10^303	hectillion
10^10^3003	killionillion
10101034	scewe's number
10^10^10^100	googolplexian
10^10^10^303	hotillion
inf	infinity

There is also the number googol, which is a 1 with 100 zeros behind it (10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000), and the number googolplex, which is a 1 with a googol of zeros behind it, (10^{10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000}) (10¹⁰¹⁰⁰). And also the number googolplexian, 1 with a googolplex number of zeros behind it. Googolplexianplex, or googolplexianplexian are still theoretical numbers, but they might have some use in real life.

The name centillion was devised in the 19th century for the 100th "illion", being 10³⁰³ in short form and 10⁶⁰⁰ in long form.

Related pages

• Order of magnitude
• Lakh
• Crore

Other websites

• Big numbers
• Counting Really,REALLY,REALLY High
• Naming Large Numbers Archived 2022-08-11 at the Wayback Machine