Large numbers

The names of large numbers in English beyond one million are based on powers of 1000, and the names of the numbers come from Latin names for the number base. For example, million is from the Latin term mille for one thousand (a thousand thousands). From there, each subsequent large number name is from the Latin names for the base number plus the suffix -illion, such as two (billion, or two powers of a thousand), three (trillion, or three powers of a thousand), four (quadrillion, or four powers of a thousand), and so on. So each number name is 1000 times the previous number (one billion = one thousand million). This is the system used widely in North America, and in modern times, in British and Commonwealth English.

1 Standard mathematical names

The names below are standard modern English names. The names for numbers up to twenty powers of a thousand (vigintillion) and for 100 powers (centillion) are standard dictionary terms. For base 20 to 99, and for numbers beyond a centillion, mathematicians have proposed a system of creating names for other numbers.

Base	Value	name
1	106	Million
2	109	Billion
3	1012	Trillion
4	1015	Quadrillion
5	1018	Quintillion
6	1021	Sextillion
7	1024	Septillion
8	1027	Octillion
9	1030	Nonillion
10	1033	Decillion
11	1036	Undecillion
12	1039	Duodecillion
13	1042	Tredecillion
14	1045	Quattuordecillion
15	1048	Quindecillion
16	1051	Sedecillion
17	1054	Septendecillion
18	1057	Octodecillion
19	1060	Novendecillion
20	1063	Vigintillion
21	1066	Unvigintillion
22	1069	Duovigintillion
23	1072	Tresvigintillion
24	1075	Quattuor­vigint­illion
25	1078	Quinvigintillion
26	1081	Sesvigintillion
27	1084	Septemvigintillion
28	1087	Octovigintillion
29	1090	Novemvigintillion
30	1093	Trigintillion
31	1096	Untrigintillion
32	1099	Duotrigintillion
33	10102	Trestrigintillion
34	10105	Quattuor­trigint­illion
35	10108	Quintrigintillion
36	10111	Sestrigintillion
37	10114	Septentrigintillion
38	10117	Octotrigintillion
39	10120	Noventrigintillion
40	10123	Quadragintillion
50	10153	Quinquagintillion
60	10183	Sexagintillion
70	10213	Septuagintillion
80	10243	Octogintillion
90	10273	Nonagintillion
100	10303	Centillion
101	10306	Uncentillion
110	10333	Decicentillion
111	10336	Undecicentillion
120	10363	Viginticentillion
121	10366	Unviginticentillion
130	10393	Trigintacentillion
140	10423	Quadra­gintacent­illion
150	10453	Quinqua­gintacent­illion
160	10483	Sexagintacentillion
170	10513	Septuagintacentillion
180	10543	Octogintacentillion
190	10573	Nonagintacentillion
200	10603	Ducentillion
300	10903	Trecentillion
400	101203	Quadringentillion
500	101503	Quingentillion
600	101803	Sescentillion
700	102103	Septingentillion
800	102403	Octingentillion
900	102703	Nongentillion
1000	103003	Millinillion

This system is called the short scale system, which differs from the long scale number systems used in Continental Europe and Latin America, where the numbers follow the pattern of million, milliard (1000 million), billion (1000 milliard), billiard (1000 billion), trillion (1000 billiard), trilliard (1000 trillion), and so on.

The numeral names like those above can be created by combining the following prefixes with the ending -illion; for example, the 142nd power would be duo + quadraginta + centillion, or one duoquadragintacentillion. To convert exponents to the power base and vice versa, the formula is 10³ⁿ⁺³, where n is the power, so the 142nd power would be 10⁴³⁵, or one followed by 435 zeroes.

Units	Ones	Tens	Hundreds
1	Un	Deci	Centi
2	Duo	Viginti	Ducenti
3	Tre(s)	Triginta	Trecenti
4	Quattuor	Quadraginta	Quadringenti
5	Quinqua	Quinquaginta	Quingenti
6	Se(s/x)	Sexaginta	Sescenti
7	Septe(n/m)	Septuaginta	Septingenti
8	Octo	Octoginta	Octingenti
9	Nove(m/n)	Nonaginta	Nongenti

2 Googol numbers

Googol is another commonly heard large number, which corresponds to 10 duotrigintillion, or 10¹⁰⁰, or 1 followed by 100 zeroes. The number was proposed by mathematician Edward Kasner in 1940, who asked his young nephew to come up with a name for a large number. He also propsed an even larger number, a googleplex, which is a one followed by a googol zeroes. The search engine Google is named after the number googol, with a spelling change, suggesting its size and scope as a search engine.

• Googol = 10¹⁰⁰ = 10 duotrigintillion
• Googolplex = 10¹⁰¹⁰⁰ or 10^googol

3 Colloquial terms

Finally, in English slang, colloquial style, dialects, and children's speech, several terms are used that suggest a very large but non-specific amount. The most popular term is zillion meaning 'some very large amount', as well as jillion, kazillion and so on. For example, in colloquial English, one might say things like "I have a zillion things to do" for the sake of emphasis or hyperbole. 

5 See also

• Metric system