半
bàn
Expressing "half" with "ban"
半 goes before the measure word for "half a", and after it for "and a half".
Number + Measure Word + 半 / 半 + Measure Word
How it works
半个小时 is half an hour. 一个半小时 is an hour and a half. The position of 半 is the whole difference.
三个半小时 — three and a half hours. Note that the measure word appears only once.
For clock times, 半 means half past: 三点半.
Examples
bàn gè xiǎo shí
半个小时
half an hour
sān gè bàn xiǎo shí
三个半小时
three and a half hours
wǒ děng le yí gè bàn xiǎo shí
我等了一个半小时。
I waited an hour and a half.