Ordinals, fractions and percent in Chinese

First, second, tenth

• An ordinal is 第 (dì) plus a number: 第一 is first, 第十 is tenth. Two is always 二 here: 第二.
• Floors, school years and months skip 第: 三楼 is the third floor, 三年级 is third grade, 三月 is March.

Grammar rule: Ordinal numbers with 第

Fractions and halves

• A fraction starts with the denominator: 三分之一 is "of three parts, one", that is 1/3.
• Half is 一半 (yíbàn), or 半 before a measure word: 半个小时 is half an hour.
• "Times" as in "twice as much" is 倍 (bèi): 两倍 is twice.

Grammar rule: Fractions with 分之

Percentages and decimals

• A percentage is "out of a hundred": 百分之 plus the number. 50% is 百分之五十.
• The decimal point is 点 (diǎn), and the digits after it are read one by one: 3.14 is 三点一四, 0.5 is 零点五.