"Amount" vs "number" - when to use each

• "The number of people attending."
• "A number of mistakes."
• "What number of items did you order?"

• "The amount of water used."
• "A large amount of money." (money is measured, not individually counted)
• "The amount of time required."

• "The amount of people" ❌ → "The number of people" ✓
• "A large number of water" ❌ → "A large amount of water" ✓

"Money" uses "amount" even though you can count individual coins or notes. This is because money as a quantity is abstract - we think of it as a sum, not individual units.

Like less/fewer, this distinction is frequently ignored in everyday speech. "The amount of mistakes" sounds wrong to careful users but is very common. In formal writing, the distinction matters.