表示數目多少或順序多少的詞叫數詞，數詞分為基數詞和序數詞。表示數目多少的數詞叫基數詞；表示順序的數詞叫序數詞。
1、基數詞：表示數目多少。
1
one
11
eleven
21
twenty-one
2
two
12
twelve
22
twenty-two
3
three
13
thirteen
30
thirty
4
four
14
fourteen
40
forty
5
five
15
fifteen
50
fifty
6
six
16
sixteen
60
sixty
7
seven
17
seventeen
70
seventy
8
eight
18
eighteen
80
eighty
9
nine
19
nineteen
90
ninety
10
ten
20
twenty
100
hundred
注意：數字「0」可以讀作「zero」，也可以讀作字母「o」。
2、序數詞：表示順序先後。
1st
first
11th
eleventh
21st
twenty-first
2nd
second
12th
twelfth
22nd
twenty-second
3rd
third
13th
thirteenth
30th
thirtieth
4th
fourth
14th
fourteenth
40th
fortieth
5th
fifth
15th
fifteenth
50th
fiftieth
6th
sixth
16th
sixteenth
60th
sixtieth
7th
seventh
17th
seventeenth
70th
seventieth
8th
eighth
18th
eighteenth
80th
eightieth
9th
ninth
19th
nineteenth
90th
ninetieth
10th
tenth
20th
twentieth
100th
hundredth
數詞變化規律及讀法口訣：
兩大數詞基和序，前表數量後第幾。構成先談基數詞，1至12請認真記。
13至19teen結尾齊，ty結尾表示幾十。若要表達幾十幾，幾十短橫1到9。One hundred 一百記，若表幾百幾十幾。幾百 and幾十幾，基數規律上述裡。再把序數談仔細，第一至三獨立記。第四至十九結尾th,第廿到九十有規律。基數基礎y變ieth。第幾十幾有特例，第幾十由基數起，幾用序數有道理。第一百one hundred。若說第一百幾十幾。One hundred and第幾十幾。談此即告一段落。序有縮式莫忘記，上述須用心體味。
3、數詞的用法
1)倍數表示法
a.主語+謂語+倍數(或分數)+ as + adj. + as
I have three times as many as you.我有你三倍那麼多。
b.主語+謂語+倍數(分數)+ the size (amount，length…) of…
The earth is 49 times the size of the moon.地球是月球的49倍。
c.主語+謂語+倍數(分數)+形容詞(副詞)比較級+ than…
The grain output is 8 percent higher this year than that of last year。
今年比去年糧食產量增加8%。
d.還可以用by+倍數，表示增加多少倍
The production of grain has been increased by four times this year。
今年糧食產量增加了4倍。
2)分數表示法
構成：基數詞代表分子，序數詞代表分母。分子大於1時，分子的序數詞用單數，分母序數詞用複數：
1/3 one-third ; 3/37 three thirty-sevenths。