几
jǐ
Measure words in quantity questions
几 asks "how many" for small numbers, and it keeps the measure word.
几 + Measure Word (+ Noun) ?
How it works
几 sits exactly where the number would: 几个人? (how many people?), 几本书? (how many books?). Because it replaces the number, the measure word stays.
几 expects an answer under about ten. For bigger or open-ended quantities, and for prices, use 多少 — which takes no measure word: 多少钱?
Examples
jǐ gè rén?
几个人？
How many people?
nǐ yǒu jǐ gè hái zi?
你有几个孩子？
How many children do you have?
nǐ men bān yǒu duō shǎo xué shēng?
你们班有多少学生？
How many students are in your class?