cardinal numbers (基数词) - ordinal numbers (序数词)

cardinal ['kɑːd(ɪ)n(ə)l]：n. 红衣主教，枢机主教，鲜红色，(北美) 主红雀 adj. 主要的，基本的，深红色的
ordinal ['ɔːdɪn(ə)l]：adj. 顺序的，依次的 n. 序数

0. 数词

数词是表示数目多少或顺序先后的词。
基数词是表示数目多少的数词。
序数词是表示顺序先后的数词。
基数词 + 序数词 = 数词

1. cardinal numbers (基数词)

基数用来表示数量。

zero ['zɪərəʊ]：num. 零
one [wʌn]：num. 一
two [tuː]：num. 二
three [θriː]：num. 三
four [fɔː]：num. 四
five [faɪv]：num. 五
six [sɪks]：num. 六
seven ['sev(ə)n]：num. 七
eight [eɪt]：num. 八
nine [naɪn]：num. 九
ten [ten]：num. 十
eleven [ɪ’lev(ə)n]：num. 十一
twelve [twelv]：num. 十二

thirteen [θɜː’tiːn; 'θɜːtiːn]：num. 十三
fourteen [fɔː’tiːn; 'fɔːtiːn]：num. 十四
fifteen [fɪf’tiːn; 'fɪftiːn]：num. 十五
sixteen [sɪks’tiːn; 'sɪkstiːn]：num. 十六
seventeen [sev(ə)n’tiːn; 'sev(ə)ntiːn]：num. 十七
eighteen [eɪ’tiːn; 'eɪtiːn]：num. 十八
nineteen [naɪn’tiːn; 'naɪntiːn]：num. 十九

twenty ['twentɪ]：num. 二十
thirty ['θɜːtɪ]：num. 三十
forty ['fɔːtɪ]：num. 四十
fifty ['fɪftɪ]：num. 五十
sixty ['sɪkstɪ]：num. 六十
seventy ['sev(ə)ntɪ]：num. 七十
eighty ['eɪtɪ]：num. 八十
ninety ['naɪntɪ]：num. 九十

thirty-five：35
sixty-seven：67
twenty-one：21
forty-six：46
seventy-eight：78
thirty-one：31
twenty-two：22
twenty-three：23
twenty-four：24
twenty-five：25
twenty-six：26
twenty-seven：27
twenty-eight：28
twenty-nine：29

hundred ['hʌndrəd]：num. 百，100
thousand ['θaʊz(ə)nd]：num. 千，1,000
million ['mɪljən]：num. 百万，1,000,000
billion ['bɪljən]：num. 十亿，1,000,000,000
trillion ['trɪljən]：num. 万亿，1,000,000,000,000

a / one hundred：100
a / one thousand：1,000
a / one million：1,000,000

1 - 12 独立成词。
13 - 19 基数词以 teen 结尾。3 - 9 基数词添加后缀 teen，thirteen 和 fifteen 例外。eight 本身有 t 字母，添加 een。
20 - 90 基数词以 ty 结尾。13 - 19 基数词后缀 teen 改为 ty，forty 例外。
21 - 99 两位数合成词，十位与个位之间添加 - 。

1.1 Separation between hundreds and tens

Hundreds and tens are usually separated by ‘and’ (in American English ‘and’ is not necessary).
hundreds and tens 通常用 ‘and’ 分隔 (用美式英语 ‘and’ 不是必需的)。
百位与十位/个位之间用 ‘and’ 分隔。

one hundred and ten - 110
one thousand, two hundred and fifty - 1,250
two thousand and one - 2,001

1.2 Hundreds

Use 100 always with ‘a’ or ‘one’. ‘a’ can only stand at the beginning of a number.

a hundred / one hundred - 100
two thousand, one hundred - 2,100

1.3 Thousands and Millions

Use 1,000 and 1,000,000 always with ‘a’ or ‘one’.

a thousand / one thousand - 1,000
two hundred and one thousand - 201,000

Use commas as a separator.

57,458,302

1,000 以上的数目，从右向左每三位用 ,。

1.4 The Number 1,000,000,000

In English this number is a billion. This is very tricky for nations where ‘a billion’ has 12 zeros. 1,000,000,000,000 in English, however, is a trillion.
在英语中，这个数字是十亿。对于 ‘a billion’ 有 12 个零的国家来说，这非常棘手。然而 1,000,000,000,000 英文是 trillion。

But don’t worry, these numbers are even a bit problematic for native speakers: for a long time the British ‘billion’ had 12 zeros (a number with 9 zeros was called ‘a thousand million’). Now, however, also in British English ‘a billion’ has 9 zeros. But from time to time this number still causes confusion.
不要担心，这些数字对于母语人士来说甚至有点问题：很长一段时间英国的 ‘billion’ 有 12 个零 (一个有 9 个零的数字称为 ‘a thousand million’)。现在，在英国英语中，‘a billion’ 有 9 个零。但是这个数字有时会引起混乱 (就像这段，我很害怕)。

1.5 Singular or Plural? (单数或者复数？)

Numbers are usually written in singular.

two hundred Euros
several thousand light years

The plural is only used with dozen, hundred, thousand, million, billion, if they are not modified by another number or expression (e.g. a few / several).

hundreds of Euros
thousands of light years

problematic [prɒblə'mætɪk]：adj. 问题的，有疑问的，不确定的
singular ['sɪŋgjʊlə]：adj. 单数的，单一的，非凡的，异常的n. 单数
plural ['plʊər(ə)l]：adj. 复数的 n. 复数
Euros ['ju:rəus]：n. 欧元

1.6 用法

表示具体数目，不用复数。
表示不确定数目，用复数。
hundreds of (数百) / thousands of (数千) / millions of (数百万) + 名词复数，可以使用 many / several 修饰，但不能与具体数目连用。

“基数词 + 度量单位 + 形容词”表示计量。
The classroom is 9 meters long, 6 meters wide and 3 meters high.

“基数词 + 名词”的合成形容词作定语，中间有连字符 -，其中的名词用单数。
a 3-year-old girl
a seven-day holiday

in + one’s + 数词复数 - 几十多岁 (in his forties - 四十多岁)
in + the + 数词复数 - 年代 (in the nineties - 九十年代)

2. ordinal numbers (序数词)

序数用来表示次序、顺序、位置。

first [fɜːst]，1st：num. 第一
second ['sek(ə)nd]，2nd：num. 第二
third [θɜːd]，3rd：num. 第三

fourth [fɔːθ]，4th：num. 第四
fifth [fɪfθ]，5th：num. 第五
sixth [sɪksθ]，6th：num. 第六
seventh ['sev(ə)nθ]，7th：num. 第七
eighth [eɪtθ]，8th：num. 第八
ninth ['naɪnθ]，9th：num. 第九
tenth [tenθ]，10th：num. 第十
eleventh [ɪ’lev(ə)nθ]，11th：num. 第十一
twelfth [twelfθ]，12th：num. 第十二
thirteenth ['θɜːtiːnθ]，13th：num. 第十三
fourteenth ['fɔː’tiːnθ]，14th；num. 第十四
fifteenth [fɪf’tiːnθ]，15th：num. 第十五
sixteenth ['sɪks’tiːnθ]，16th：num. 第十六
seventeenth [,sevən’tiːnθ]，17th：num. 第十七
eighteenth ['eɪ’tiːnθ]，18th：num. 第十八
nineteenth ['naɪn’tiːnθ]，19th：num. 第十九

twentieth [ˈtwentɪəθ]，20th：num. 第二十
thirtieth ['θɜːtɪɪθ]，30th：num. 第三十
fortieth ['fɔːtɪɪθ]，40th：num. 第四十
fiftieth ['fɪftɪɪθ]，50th：num. 第五十
sixtieth ['sɪkstɪθ]，60th：num. 第六十
seventieth ['sevəntɪɪθ]，70th：num. 第七十
eightieth ['etɪɪθ]，80th：num. 第八十
ninetieth ['naɪntɪɪθ]，90th：num. 第九十

thirty-first，31st
sixty-second，62nd
eighty-third，83rd
ninety-eighth，98th
twenty-first，21st
twenty-second，22nd
twenty-third，23rd
twenty-fourth，24th
twenty-fifth，25th
twenty-sixth，26th
twenty-seventh，27th
twenty-eighth，28th
twenty-ninth，29th

hundredth ['hʌndrədθ]：num. 第一百 n. 百分之一
100th
thousandth ['θaʊzəntθ]：num. 第一千 n. 千分之一
1000th
millionth ['mɪljənθ]：num. 第一百万 n. 百万分之一
1000000th
billionth ['bɪljənθ]：num. 第十亿 n. 十亿分之一
trillionth ['trɪljənθ]：num. 第一万亿 n. 万亿分之一

八少 t，九去 e，ve 要用 f 替。
20th - 90th 基数词尾 ty 中的 y 改成 ie，加上后缀 th。
21 - 99 把个位的基数词变为序数词。
序数词缩写：数字 + 最后两字母

2.1 Spelling of Ordinal Numbers

Just add th to the cardinal number:

four - fourth
eleven - eleventh

Exceptions:

one - first
two - second
three - third

five - fifth
eight - eighth
nine - ninth
twelve - twelfth

In compound ordinal numbers, note that only the last figure is written as an ordinal number.
请注意只有最后一个数字被写为序数。

421st = four hundred and twenty-first
5,111th = five thousand, one hundred and eleventh

2.2 Figures

When expressed as figures, the last two letters of the written word are added to the ordinal number.
当表示为数字时，书面文字的最后两个字母被添加到序数中。

first = 1st
second = 2nd
third = 3rd
fourth = 4th
twenty-sixth = 26th
hundred and first = 101st

2.3 Titles

In names for kings and queens, ordinal numbers are written in Roman numbers. In spoken English, the definite article is used before the ordinal number.
在国王和王后的名称中，序数用罗马数字写成。在英语口语中，在序数之前使用定冠词。

Charles II - Charles the Second
Edward VI - Edward the Sixth
Henry VIII - Henry the Eighth

2.4 用法

序数词作定语，前面加 the 或形容词性物主代词，前面加 a / an 表示“再一”，“又一”的意思。

表示顺序时可以采用如下形式：
名词 + 基数词
the + 序数词 + 名词