Ⅰ.数词的分类
1.基数词
表示数目的词称为基数词。其形式如下：
A.从1-10
one，two，three，four，five，six，seven，eight，nine，ten.
B.从11-19
eleven，twelve， thirteen， fourteen， fifteen， sixteen， seventeen，eighteen， nineteen
The boy is in his teens.
C.从21-99
除twenty，thirty, forty，fifty，eighty为特殊形式外，sixty，seventy，ninety都是其个位数形式后添加后缀-ty构成。
21 twenty-one
76 seventy-six
D.百位数
个数基数词形式加“hundred”，表示几百，在几十几与百位间加上and.
101 a hundred and one
320 three hundred and twenty
648 six hundred and forty-eight
E.千位数以上
从数字的右端向左端数起，每三位数加一个逗号“，”。从右开始，第一个“，”前的数字后添加 thousand，第二个“，”前面的数字后添加 million，第三个“，”前的数字后添加 billion。然后一节一节分别表示，两个逗号之间最大的数为百位数形式。
2,648 two thousand，six hundred and forty-eight
16,250,064 sixteen million，two hundred and fifty thousand and sixty-four
5,237,166,234 five billion，two hundred and thirty-seven million，one hundred and sixty-six thousand，two hundred and thirty-four
F.基数词在表示确切的数字时，不能使用百、千、百万、十亿的复数形式；但当基数词表示不确切数字，如成百、成千上万、三三两两时，基数词则以复数形式出现。
There are hundreds of people in the hall.
Thousands and thousands of people come to visit the Museum of Qin Terra-Cotta Warriors and Horses every day.
They went to the theatre in twos and threes.
G.表示人的不确切岁数或年代，用几十的复数形式表示。
He became a professor in his thirties.
She died of lung cancer in her forties.
It was in the 1960s.
H.基数词的句法功能
基数词在句中可作主语、宾语、定语、表语、同位语。
The two happily opened the box.
I need three altogether.
Four students are playing volleyball outside.
We are sixteen.
They three tried to finish the task before sunset.
2.序数词
表示顺序的词称为序数词。序数词的主要形式：
A.从第一至第十九
其中，one-first， two-second， three-third， five-fifth，eight-eighth，nine-ninth，twelve-twelfth为特殊形式，其它的序数词都是由其相对应的基数词后面添加“th”构成。例如： six-sixth、nineteen-nineteenth.
B.从第二十至第九十九
整数第几十的形式由其对应的基数词改变结尾字母y为i，再加“eth”构成。
twenty-twentieth thirty-thirtieth
表示第几十几时，用几十的基数词形式加上连字符“-”和个位序数词形式一起表示。
thirty-first
fifty-sixth
seventy-third
ninety-ninth
C.第一百以上的多位序数词
由基数词的形式变结尾部分为序数词形式来表示。
one hundred and twenty-first
one thousand，three hundred and twentieth
D.序数词的缩写形式
有时，序数词可以用缩写形式来表示。主要缩写形式有。
first-lst second-2nd third-3rd
fourth-4th sixth-6th twentieth-20th
twenty-third-23rd
其中lst，2nd，3rd为特殊形式，其它的都是阿拉伯数字后加上th。
E.序数词的句法功能
序数词在句中可作主语、宾语、定语和表语。
The second is what I really need.
He chose the second.
We are to carry out the first plan.
She is the second in our class.
注：序数词在使用时，通常前面要加定冠词 the;但是如果序数词前出现不定冠词a或an时，则表示“再——”，“又——”。
We’ll go over it a second time.
We’ve tried it three times.Must we try it a fourth time?
Ⅱ.时刻表示法
five o’clock 或 five
five past seven
half past six
a quarter past eight
seven past eight
ten to eight
a quarter to twelve
twenty to six
在日常生活中，常用下列简单方法表示时间。
six thirty-one
ten twenty-six
fourteen o three
sixteen fifteen
eighteen thirty
twenty-three fifty-five
注：时刻表上的时间大多采用24小时表示法，这样就不需要用a.m.表示上午，p.m.表示下午了。
Ⅲ.年月表示法
1.世纪
the sixth(6th)century
the eighteenth(18th)century
the 1900s
the 1600s
2.年代
in the 1930s
in the 1860s
In the 1870s when Marx was already in his fifties, he found it important to study the situation in Russia，so he began to learn Russian.
3.表示某年代的早期、中期和晚期，可以在定冠词后，年代前添加 early，mid-，late
in the early 1920s
in the mid-1950s
4.年月日表示法
January，February，March，April
May，June，July，August，September
October，November，December
On Oct.15,1949
In Dec.1902
Ⅳ.分数表示法
分数是由基数词和序数词一起来表示的。基数词作分子，序数词作分母，除了分子是“1”以外，其它情况下序数词都要用复数形式。本文|由职业培训教育网独家整理。
3/4 three fourths或 three quarters
1/3 one third或a third
24/25 twenty-four twenty-fifths
3 1/4 three and one fourth或 three and one quarter
1/2 a half
1/4 one quarter或a quarter
1 1/2 one and a half
1 1/4 one and a quarter
Ⅴ.小数表示法
0.4 zero point four或point four
10.23 ten point two three
25.67 twenty-five point six seven
l.03 one point o three
Ⅵ.百分数表示法
百分数用基数+percent表示
50% fifty percent
3% three percent
0.12% zero point one two percent
