Hello.

I search in oxford dictionary and see that "number" can refer to a quantity of people or thing, a symbol, or group of people. The problem is that I cannot tell when "number" refers to one of these meanings.

And it seems to me that "quantity" has the same meaning as "a group of people or thing". Is it correct?

For example:

(1) "A large number of people have applied for the job" -- the dictionary give the example to illustrate the meaning "quantity", but I do not see the difference if I think of "a large number of people" as a group of people.

(2) The number of homeless people has increased dramatically. -- the dictionary give the example to illustrate the meaning "quantity", but to me "The number" seems to refer to a symbol. How a group of people could fall?

Please explain and give examples when we use "number" to refer one of the above meaning of "number".
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through question 70 in review verbal 2, I know that when used in comparison, "X's numbers" must go with "greater", not "more".

do "The number" and "A number" follow the rule?

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Through the question 70, I also see that a contradiction.

X's numbers is now five times greater than the past.

but

He is five times as old as his grandson.

do "The number" and "A number" follow the rule, as "X's numbers" does?

Thank you.