"Kolik nohou mají mouchy?"

Translation: How many legs do flies have?

[Shathu_Entayla]

Is "nohou" in intrumental here? Why? I thought that "kolik" needed genitive O.o.

[VladaFu]

It is genitive (dual) https://en.wiktionary.org/wiki/noha#Declension .

[jgreenemi]

"How many feet" is not accepted?

[VladaFu]

I am not sure flies have any feet, but one usually speaks about legs in insects... And

But even if they do I fear they are not called nohy in Czech, they would be chodidla or something like that.