几【jǐ】

几 asks "how many" when you expect a small answer, roughly ten or fewer. It works like a number, so a measure word always follows it.

• × 你有几哥哥？ → 你有几个哥哥？

几 or 多少

几 expects a handful. 多少 puts no limit on the answer, and the measure word after it is optional.

A family or the books on a desk take 几. A price, a population or a crowd takes 多少.

Time and date

几点 asks the time, 几号 the day of the month and 星期几 the day of the week. These are set phrases, so 几 stays even where the answer can go past ten.

几 as "a few"

In a statement rather than a question, 几 means "a few" or "several". 十几 is "ten-something" and 几十 "a few dozen".