二 / 两【èr / liǎng】

Chinese has two words for "two" and they are not interchangeable. 两 counts things; 二 is the digit.

两 before a measure word

Anything being counted takes 两. èr二gè rén个人 is wrong.

二 when the number is being read out

Counting aloud, reciting digits, giving a date, a room number, a bus route or an ordinal – all 二.

Inside larger numbers

In the tens and units, 二: 十二, 二十二, 三十二. In front of 百, 千 and 万 it is usually 两: 两百, 两千, 两万. 二百 is also heard in the north.

Telling the time

两点 is two o'clock, but 二十分 is twenty minutes past, because 二十 is a number being read out.