"How many siblings do you have?"

Translation: 你有几个兄弟姐妹？

[samertabbal]

几位

[LlamaScota]

Is 几个 used for countable nouns and 多少 used for uncountable nouns?

[richard711603]

几个 is used for small numbers and 多少 for larger numbers. In general 几个 is use when the answer would be 10 or less. Look at the tips in Payment and Time-1.

[Bilbao77]

你们有。。。not accepted. How exactly are people expected to know if it's singular or plural you?

[richard711603]

I think 个 is not necessary. Will a native speaker clarify.

[George792719]

I didn't add the 个and was marked correct, so it must be acceptable.

[The_Tams]

I did not add the 个 and was marked incorrect.