Как правильно задавать вопрос «Сколько из нас (… из вас, … из них)»?

Текстовая расшифровка урока:

Let’s start today’s podcast by looking at the title – “How many of us are there?” The title is asking a question – “How many people are there in Britain?” But instead of talking about “people in Britain”, I have used a pronoun – “us”. And when we use a pronoun after “how many” or “how much”, we have to use the little word “of” as well. So “How many of us are there?” – not “how many us are there?”

Here are some more examples. Suppose that you and a group of friends go to the cinema. You go to the ticket desk to buy the tickets, but you are not sure how many tickets you need to buy. So, you shout to your friends, who are busy buying popcorn, “How many of us are there?” One of your friends counts, and shouts “Six”. So you buy six tickets.

Imagine a class of children at school. They are doing a project about how they travel to school each day. The teacher asks “How many of you come to school on the bus? How many of you walk to school?”

And finally, two small boys are collecting cards with pictures of famous footballers on them. The cards are free inside packets of sweets. There are 50 different cards, with 50 different footballers, altogether. “I have got 20 different players”, says one boy. “How many of them have you got?”