Large Numbers

United States
Nomenclature for large numbers varies in different countries. In the United States, numbers advance by increments of a thousand:
billion	1,000,000,000	1 × 109
trillion	1,000,000,000,000	1 × 1012
quadrillion	1,000,000,000,000,000	1 × 1015
United Kingdom and Germany
However, in the UK and Germany numbers have traditionally advanced by increments of a million:
million	1,000,000	1 × 106
billion	1,000,000,000,000	1 × 1012
trillion	1,000,000,000,000,000,000	1 × 1018
quadrillion	1,000,000,000,000,000,000,000,000	1 × 1024
This has a certain amount of logic on its side, particularly for classical scholars:
billion =	million2	(bi-)
trillion =	million3	(tri-)
quadrillion =	million4	(quadr-)
Higher numbers
The U.S. usage is becoming prevalent in the UK and Germany, particularly as it is now universally used by economists and statisticians. The higher numbers, in both styles, are as follows:
Number	United States	United Kingdom
quintillion	1 × 1018	1 × 1030
sextillion	1 × 1021	1 × 1036
septillion	1 × 1024	1 × 1042
octillion	1 × 1027	1 × 1048
nonillion	1 × 1030	1 × 1054
decillion	1 × 1033	1 × 1060
vigintillion	1 × 1063	1 × 10120
centillion	1 × 10303	1 × 10600