The word "number" is a general term which refers to a member of a given (possibly ordered) set. The meaning of "number" is often clear from context (i.e., does it refer to a complex number, integer, real number, etc.?). Wherever possible in this work, the word "number" is used to refer to quantities which are integers, and "constant" is reserved for nonintegral numbers which have a fixed value. Because terms such as real number, Bernoulli number, and irrational number are commonly used to refer to nonintegral quantities, however, it is not possible to be entirely consistent in nomenclature.

To indicate a particular numerical label, the abbreviation "no." is sometimes used (deriving from "numero," the ablative case of the Latin "numerus"), as is the less common "nr." The symbol # (known as the octothorpe) is commonly used to denote "number."

While some authors prefer to include "and" between various parts of a number name, in this work, "and"s are omitted. For example, the number 101 is
called "one hundred one" rather than "one hundred and one." According
to most definitive sources (Schildberger 2001; *The Chicago Manual of Style*
2003, p. 381; Mish 2003, p. 852), either is acceptable. However, *The
Associated Press Stylebook* gives implicit examples in which the "and"
is omitted (Goldstein 1998, p. 145). So the fact of the matter is that different
sources use different conventions, with some sources even being internally inconsistent.
For example, Conway and Guy (1996) list the "(and)" as optional on p. 15,
while writing out "one hundred and sixty-three" on p. 25.

According to *The Chicago Manual of Style* (2003, p. 380), in nontechnical written contexts, whole numbers from one to one hundred should always be spelled
out, and other whole numbers should be written in terms of numerals. In addition,
when a number begins a sentence, it is always spelled out unless it appears awkward,
in which case the sentence should be recast. In this work, numbers are sometimes
spelled out and sometimes written numerically, depending on which appears clearer.

Note that commas should not be used to separate words that are part of one number (Goldstein 1998, p. 145).

The following table summarizes the English names given to the first few positive numbers (Schildberger 2001, Misch 2003).

name | |

1 | one |

2 | two |

3 | three |

4 | four |

5 | five |

6 | six |

7 | seven |

8 | eight |

9 | nine |

10 | ten |

11 | eleven |

12 | twelve |

13 | thirteen |

14 | fourteen |

15 | fifteen |

16 | sixteen |

17 | seventeen |

18 | eighteen |

19 | nineteen |

20 | twenty |

21 | twenty-one |

22 | twenty-two |

23 | twenty-three |

24 | twenty-four |

25 | twenty-five |

26 | twenty-six |

27 | twenty-seven |

28 | twenty-eight |

29 | twenty-nine |

30 | thirty |

31 | thirty-one |

32 | thirty-two |

33 | thirty-three |

34 | thirty-four |

35 | thirty-five |

36 | thirty-six |

37 | thirty-seven |

38 | thirty-eight |

39 | thirty-nine |

40 | forty |

41 | forty-one |

42 | forty-two |

43 | forty-three |

44 | forty-four |

45 | forty-five |

46 | forty-six |

47 | forty-seven |

48 | forty-eight |

49 | forty-nine |

50 | fifty |

51 | fifty-one |

52 | fifty-two |

53 | fifty-three |

54 | fifty-four |

55 | fifty-five |

56 | fifty-six |

57 | fifty-seven |

58 | fifty-eight |

59 | fifty-nine |

60 | sixty |

61 | sixty-one |

62 | sixty-two |

63 | sixty-three |

64 | sixty-four |

65 | sixty-five |

66 | sixty-six |

67 | sixty-seven |

68 | sixty-eight |

69 | sixty-nine |

70 | seventy |

71 | seventy-one |

72 | seventy-two |

73 | seventy-three |

74 | seventy-four |

75 | seventy-five |

76 | seventy-six |

77 | seventy-seven |

78 | seventy-eight |

79 | seventy-nine |

80 | eighty |

81 | eighty-one |

82 | eighty-two |

83 | eighty-three |

84 | eighty-four |

85 | eighty-five |

86 | eighty-six |

87 | eighty-seven |

88 | eighty-eight |

89 | eighty-nine |

90 | ninety |

91 | ninety-one |

92 | ninety-two |

93 | ninety-three |

94 | ninety-four |

95 | ninety-five |

96 | ninety-six |

97 | ninety-seven |

98 | ninety-eight |

99 | ninety-nine |

100 | one hundred |

101 | one hundred one |

102 | one hundred two |

103 | one hundred three |

104 | one hundred four |

105 | one hundred five |

106 | one hundred six |

107 | one hundred seven |

108 | one hundred eight |

109 | one hundred nine |

110 | one hundred ten |

111 | one hundred eleven |

112 | one hundred twelve |

113 | one hundred thirteen |

114 | one hundred fourteen |

115 | one hundred fifteen |

116 | one hundred sixteen |

117 | one hundred seventeen |

118 | one hundred eighteen |

119 | one hundred nineteen |

120 | one hundred twenty |

121 | one hundred twenty-one |

122 | one hundred twenty-two |

123 | one hundred twenty-three |

124 | one hundred twenty-four |

125 | one hundred twenty-five |

126 | one hundred twenty-six |

127 | one hundred twenty-seven |

128 | one hundred twenty-eight |

129 | one hundred twenty-nine |

130 | one hundred thirty |

131 | one hundred thirty-one |

132 | one hundred thirty-two |

133 | one hundred thirty-three |

134 | one hundred thirty-four |

135 | one hundred thirty-five |

136 | one hundred thirty-six |

137 | one hundred thirty-seven |

138 | one hundred thirty-eight |

139 | one hundred thirty-nine |

140 | one hundred forty |

141 | one hundred forty-one |

142 | one hundred forty-two |

143 | one hundred forty-three |

144 | one hundred forty-four |

145 | one hundred forty-five |

146 | one hundred forty-six |

147 | one hundred forty-seven |

148 | one hundred forty-eight |

149 | one hundred forty-nine |

150 | one hundred fifty |

Note that two differing conventions exist for the naming of large numbers (e.g., the American system terms "a billion," while the British system terms it "a milliard").

American | British | power of 10 |

million | million | |

billion | milliard | |

trillion | billion | |

quadrillion | ||

quintillion | trillion | |

sextillion | ||

septillion | quadrillion | |

octillion | ||

nonillion | quintillion | |

decillion | ||

undecillion | sexillion | |

duodecillion | ||

tredecillion | septillion | |

quattuordecillion | ||

quindecillion | octillion | |

sexdecillion | ||

septendecillion | nonillion | |

octodecillion | ||

novemdecillion | decillion | |

vigintillion | ||

undecillion | ||

duodecillion | ||

tredecillion | ||

quattuordecillion | ||

quindecillion | ||

sexdecillion | ||

septendecillion | ||

octodecillion | ||

novemdecillion | ||

vigintillion | ||

centillion | ||

centillion |

The numbers of characters (including spaces and dashes) in the English names (written without trailing "and"s) for the numbers 1, 2, 3, ... are 3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, 6, 8, 8, 7, 7, 9, 8, 8, 6, 10, 10, ... (OEIS A052360), illustrated above.

The corresponding numbers of letters are 3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, 6, 8, 8, 7, 7, 9, 8, ... (OEIS A005589; *Eureka*
1974), illustrated above.

The corresponding numbers of syllables are 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2, 2, ... (OEIS A075774).

Consider the numbers having incrementally largest numbers of letters. This gives the sequence 1, 3, 11, 13, 17, 23, 73, 101, 103, 111, 113, 117, 123, 173, 323, 373, ... (OEIS A052363), which have the corresponding number of digits 3, 5, 6, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21, ... (OEIS A089585).