2. 小数：小数总是用阿拉伯数字表达。小数点后不论有多少位都不能用逗号分开，但小数点之前的数依然按照三位一个逗号的原则书写。

0.786432 120,372.428

注意：小数点前的数按普通基数词的读法读，小数点后的数每一位都要单独读。

15.503 读作fifteen point five zero three

0.05 读作zero point zero five

3. 百分数：百分数中的数目用阿拉伯数字，后接percent或百分号（%），在专业统计或表格中常用%代替percent，在句首时则用英语单词书写。

I have invested 40 percent of my income.

我把40%的收入用作投资了。

Farmers’ income has increased by 30%.

农民的收入已经增加了30%。

4、 倍数：表示倍数时，一倍用once，两倍 用twice/double，三倍以上用“基数词+ times”。

1）“倍数 + as many/much … as …”

My deskmate clamed to have twice as many stamps as I.

我同桌声称他的邮票是我的两倍。

This computer costs three times as much as that one.

这台计算机的价格是那台的三倍。

2）“倍数 + the size of …”

用法与size相同的名词常见的有weight（重量），height（高度），depth（深度），width（宽度），age（年龄），length（长度）等。

Our playground is five times the size of theirs.

我们的操场是他们的五倍大。

This street is twice/double the width of that one.

这条大街是那条大街的两倍宽。

3）“倍数 + what从句”

The value of the house is double what it was.

这所房子的价值是原来的两倍。

People’s average income is almost five times what they earned ten years ago.

人们的平均收入是十年前的五倍。

4）“倍数 + 比较级 + than”

The room is twice larger than ours.

这间房子比我们的房子大两倍。

This ball seats three times more people than that one.

这个大厅能坐的人数是那个大厅的四倍。

5）“比较级 + than … + by + 倍数/程度”

The line is longer than that one by twice.

这根线是那根线的两倍长。

The population of China is larger than that of the US by over 6 times.

中国人口是美国人口的六倍多。

5、四则运算：

1）加法：在口语中，小数目的加法常用and代表“+”，is 或 are 代表“=”。

在正式的场合或较大数目的加法用plus代表“+”，equals或is 代表“=”。

7+4=11 Seven and four is/are eleven.

13+12=25 Thirteen plus twelve equals/is twenty-five.

2) 减法：在口语中，小数目的减法用“Take away + 减数 + from + 被减数 + and you get + 余数”

“减数 + from + 被减数 + leaves/is + 余数”

在正式的场合或较大数目的减法用minus 代表“—”，equals 代表“=”。

12-5=7 Five from twelve leaves/is seven. /Take away five from twelve and you get seven.

21-7=14 Twenty-one minus seven equals fourteen.

3) 乘法：在口语中，小数目的乘法的乘数用复数形式，用are 代表“=”。

大数目的乘法用times代表“×”，is/makes 代表“=”。

在正式的场合下用multiplied by 代表“×”，equals 代表“=”。

4×5=20 Four fives are twenty

326×238=77588 Three hundred and twenty-six times two hundred and thirty-eight is/makes seventy-seven thousand five hundred and eighty-eight.

Three hundred and twenty-six multiplied by two hundred and thirty-eight equals seventy-seven thousand five hundred and eighty-eight.

4) 除法：小数目的除法：用divided by 代表“÷”，equals 代表“=”。

“被除数 + divided by + 除数 + equals + 商”；“除数 + into + 被除数 + goes + 商”

32÷4=8 Thirty-two divided by four equals eight.

Four into thirty-two goes eight.

大数目的除法：用divided by 代表“÷”，equals 代表“=”。

216÷8=27

Two hundred and sixteen divided by eight equals twenty-seven.

6、比率：一般来说表示比率都用阿拉伯数字（包括句首的情况），但在非专业性的文字中，也可用英语单词的形式。

The ratio of 7 to 4 is written 7:4 or 7/4.

七比四写作7:4或7/4。

You have a fifty to fifty chance of success.

你成功的机会只有一半。

7、编号：用基数词时 名词 + 基数词 World War Ⅰ/Page 8/Room 109…

用序数词时 the + 序数词 + 名词 the First World War

8、年代与几十几岁：通常是逢十的基数词用作复数形式。表示年代的数词前用定冠词 in the 90s；表示岁数的数词前用形容词用物主代词 in one’s twenties

9、约数：1）表示“大约”可以用about/some/around/nearly/something like/more or less，用or so 表示“左右、大约”置于数词之后。

The man in rags is about/some sixty years old.

The man in rags is sixty years old or so.

那个衣衫褴褛的男子大约有六十岁/六十岁左右。

Peter is something like thirty.

皮特大约有三十岁。

2）“多于、超过”用more/than/over/above；“少于、不超过”用less than。

She was more than/less than forty when she got married.

她结婚时有四十多岁/不到四十岁。

3）其他

半天（小时）half a day=a half day; half an hour=a half hour

一个半 a day and a half=one and a half days

两天半 two days and a half=two and a half days

一两天……one or two days=a day or two

两三天/周/个苹果 a couple of days/weeks/apples…

三番五次 again and again; repeatedly; time and (time) again; over and over again; time after time

三年五载 from three to five years; in a few years

三三两两 in twos and threes; in knots