A percentage is a portion of a whole expressed as a number between 0 and 100 rather than as a fraction. All of something is 100 percent, half of it is fifty percent, none of something is zero percent.
To determine a percentage, you divide the portion of the whole by the whole itself and multiply by 100. So if you just ate two pieces of an eight-piece pie, and you want to know what percentage of the pie you consumed, you'd first divide 2 by 8 which equals .25. Then multiply .25 times 100 and get 25 percent. A percentage can also mean a portion of something but only when it has to do with numbers. When you buy furniture, the salesman gets a percentage of what you spend.