Amount of / number of

The times I’ve seen these words confused!
Number + things that can be counted.
Amount + a quantity of something uncountable. (eg: milk) Compare to:fewer/less.

A number of..

  1. problems
  2. boyfriends
  3. business deals
  4. classes
  5. hobbies
  6. debts that you owe
  7. 10-pound notes.

These are all things that can be counted individually: 3 boyfriends, 6 business deals, 4 classes, 8 debts, twelve 50-dollar bills, and a whole lot of problems.

On the other hand, you can have an amount of ..

  1. debt
  2. confusion
  3. money
  4. compassion.

These cannot be separated into individual items. For example, while you can have 3 debts to repay, each one a separate debt, debt (without the –s) cannot be separated; it is a mass concept.

Amount Of

The 'amount of' is used for uncountable nouns. (usually before a singular noun).

Examples:

I undertook an inordinate amount of work. (work - singular and cannot be measured or counted)

She had a certain amount of respect for the sales team, but she always dissented when they spoke at meetings. (respect - singular and cannot be measured or counted)

It is not difficult to see where that amount of hate derives. (hate - singular and cannot be measured or counted) Quantity Of The term 'quantity of' is used for things that you can measure. (See countable nouns). It is usually applied to inanimate objects. Some grammar references may advocate that it can only precede a singular word; however, this view is now considered outdated.

Examples:

I took control of a large quantity of money. (money - singular and can be measured or counted)

The ship was only carrying a large quantity of mangoes. (mangoes - plural and can be measured or counted) ('Number of' could also be used in this example. 'Number of' is preferable as it is unlikely to be considered incorrect by some readers.)

Number Of

'number of' precedes a plural, countable noun. It can be applied to both animate and inanimate objects.

Examples:

  1. The disease affected a large number of camels in the town. (camels - plural, animate and can be counted)
  2. The ship was only carrying a large number of mangoes. (mangoes - plural, inanimate and can be counted) ('Quantity of' could also be used in this example.)