Amount refers to quantity that cannot be counted.We should not be confused by "an amount of money." True, we can count money, but we don't count "one money, two moneys," etc.
The amount of work accomplished before a major holiday is always negligible.
Number, in contrast, refers to things that can be counted.
He has held a number of jobs in the past five months.
The most common mistake of this kind is to refer to an “amount" of people instead of a “number" of people.
But some concepts, like time, can use either amount or number, depending on how the elements are identified in the specific sentence:
We were surprised by the amount of time it took us to settle into our new surroundings.
The number of hours it took to repair the sink pleased us.
The amount of food wasted in the United States each day is appalling.
Note The number of pounds of food wasted in the United States each day is appalling.
He had a small amount of ammunition left.
He had a small number of bullets left.