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US system

Name                 Value in powers of ten  Number of zeros  

Number of groups of three 

zeros after 1000

billion 109 9 2
trillion 1012 12 3
quadrillion 1015 15 4
quintillion 1018 18 5
sextillion 1021 21 6
septillion 1024 24 7
octillion 1027 27 8
nonillion 1030 30 9
decillion 1033 33 10
undecillion 1036 36 11
duodecillion 1039 39 12
tredecillion 1042 42 13
quattuordecillion 1045 45 14
quindecillion 1048 48 15
sexdecillion 1051 51 16
septendecillion 1054 54 17
octodecillion 1057 57 18
novemdecillion 1060 60 19
vigintillion 1063 63 20
centillion 10303 303 100

British system

Name Value in powers of ten Number of zeros Powers of 1 000 000
milliard 109 9
billion 1012 12 2
trillion 1018 18 3
quadrillion 1024 24 4
quintillion 1030 30 5
sextillion 1036 36 6
septillion 1042 42 7
octillion 1048 48 8
nonillion 1054 54 9
decillion 1060 60 10
undecillion 1066 66 11
duodecillion 1072 72 12
tredecillion 1078 78 13
quattuordecillion 1084 84 14
quindecillion 1090 90 15
sexdecillion 1096 96 16
septendecillion 10102 102 17
octodecillion 10108 108 18
novemdecillion 10114 114 19
vigintillion 10120 120 20
centillion 10600 600 100

Note: To avoid ambiguity, the US system of naming these denominations is increasingly being adopted in Australia and elsewhere in the world, including Britain.