الى الاساتذة الكرام رجاءا الرد عليا من اى مدرس ضرورى لو سمحتم

[Mr. Jan]

While the number of cars is
a number of cars are
The first sentence has a meaning if it points at a group as individuals then it takes plural verb
while if it has a meaning of a group as a unit it takes sing. v