Name: Sally

Who is asking: Other
Level: Middle

Question:
If 20% of 100 is 80, then why is the percentage difference between 80 and 100 25%.

Percent means per one-hundred so 20% of 100 is

The second part of your question raises another problem. When you ask a percentage question you need to ask percentage of what. When you say the difference between 80 and 100 is 25% you need to say 25% of what. Consider this example. You buy an item for $80 and you want to mark it up to sell it. If you mark it up 25% (that is 25% of what it cost you) then you mark it up

As a second example suppose that a shop owner has an item which sells for $100. She decides to put it on sale for $80, and thus marks it down $20. In this case she would say reduced by 20%. Here she means that the price has been reduced by 20% of the original price of $100.