Number is used for words that we can count. We can use number to talk about objects and living things:
A large number of people have applied for the job.
I could give you any number of reasons for not going.
Amount is used to talk about things we can’t count:
We’ve had an enormous amount of help from people.
The sauce has just the right amount of salt.
Quantity is used to talk about both countable and uncountable things . It is used to talk about objects, but not living things.
They were surprised by the sheer quantity of food.
A large quantity of books were sold.
We also often say: “in large/small/huge quantities”
It is a product that is cheap to produce in large quantities.
Coffee is consumed in vast quantities around the world.
