NAMING LARGE NUMBERS

To name a large number, first change the number into one which is expressed as N x 10n, where n is a multiple of 3 and N is between 1 and 999 (starting at the end of the number, use commas to break the number up into groups of three digits). Read N in the normal fashion, followed by the correct word from the list below for the rest of the number. (If the power of 10 is larger than 120, proceed to the bottom of the page.)

Example: 45000000000000000000000000000000000000000000
       = 45,000,000,000,000,000,000,000,000,000,000,000,000,000,000
       = 45 x 1042
       = 45 tredecillion

million
106
billion
109
trillion
1012
quadrillion
1015
quintillion
1018
sextillion
1021
septillion
1024
octillion
1027
nonillion
1030
decillion
1033
undecillion
1036
dodecillion
1039
tredecillion
1042
quattuordecillion
1045
quindecillion
1048
sexdecillion
1051
septendecillion
1054
octodecillion
1057
novemdecillion
1060
vigintillion
1063
unvigintillion
1066
dovigintillion
1069
trevigintillion
1072
quattuorvigintillion
1075
quinvigintillion
1078
sexvigintillion
1081
septenvigintillion
1084
octovigintillion
1087
novemvigintillion
1090
trigintillion
1093
untrigintillion
1096
dotrigintillion
1099
tretrigintillion
10102
quattuortrigintillion
10105
quintrigintillion
10108
sextrigintillion
10111
septentrigintillion
10114
octotrigintillion
10117
novemtrigintillion
10120
RULES FOR NAMING LARGER POWERS OF TENS
(adapted from The Book of Numbers by Conway and Guy)
STEP
EXAMPLE
Start with a power of ten that is a multiple of three.
102484
Take that power of 10 and subtract 3.
2484 - 3 = 2481

Divide the result by 3.

2481 / 3 = 827

Starting at the end of the quotient, find each of the prefixes in the table below, ones digit first, tens digit next, etc. (The letters in parentheses are explained in the next step.)

7 = septe (mn)
2 = (ms) viginti
8 = (mx) octingenti

String the segments together, inserting an extra letter if the letter shown in parentheses at the end of one segment matches a letter in parentheses at the beginning of the next.

septemvigintioctingenti

(The m was added between septe and viginti because m was in each pair of parentheses.)

If the result ends in a, change the a to i.

septemvigintioctingenti

(Rule doesn't apply here.)

Add llion at the end, and you're done!

septemvigintioctingentiillion
PREFIXES
digit
ones
digit
tens
digit
hundreds
digit
thousands
digit
0
1
un  (n) deci  (nx) centi  mille 
2
duo  (ms) viginti  (n) ducenti 
3
tre (s)  (ns) triginta (ns) trecenti 
4
quattuor  (ns) quadraginta (ns) quadringenti 
5
quinqua  (ns) quinquaginta (ns) quingenti 
6
se (sx)  (n) sexaginta (n) sescenti 
7
septe (mn)  (n) septuaginta (n) septingenti 
8
octo  (mx) octoginta (mx) octingenti 
9
nove (mn)  nonaginta nongenti 
NOTE: The above is all based on the American system of naming numbers. The British do it differently. To see a comparsion between the two systems, click HERE.