What is 80% off $100?

How is 80% off $100 determined?

The long formula for determining percentage off is (100 - percent) / 100 * amount. In this case, it would be (100 - 80) / 100 * 100, for an answer of $20.00.

However, if you can do some quick math in your head, you can also subtract the percentage from 100, add a decimal point before that number, and multiply that number by the amount. So, using the same example, you would multiply 0.2 (100 - 80 with the decimal added before the 20) by 100 for the same answer of $20.00. Unless you're really good, you'll probably need a calculator for anything other than very common percentages and amounts.

Percentages off chart for $100

80.01% - 80.99% off chart for $100