وَيُسْأَلُ بِـ«كَمْ» عَنِ الْعَدَدِ
Kam asks about number.
كَمْ كِتَابًا عِنْدَكَ؟
How many books do you have?
A suitable answer is 'five books.' Kam does not ask for an object's essential nature or a person's identity; it requests a count of members of a class.
An interrogative kam may be followed by a specification indicating the counted item. The grammatical form of that specification depends on the kind of kam and its construction; consequently interrogative kam must be distinguished from the exclamatory/declarative use emphasizing multitude.