Percent

A percentage is a way of expressing a number as a fraction of 100, written with the symbol %. Saying "per cent" literally means "per hundred," so 25% is simply 25 out of every 100, or one quarter of the whole. Its great strength is comparability: because everything is scaled to the same base of 100, percentages let you compare proportions of very different sizes on equal footing. A value can also exceed 100%, which happens whenever a part is larger than the reference amount, such as growth that more than doubles. In everyday life percentages appear almost everywhere, from discounts and sales tax to interest rates, exam scores, and battery levels. In finance and economics they measure returns, inflation, and price changes, while in statistics they turn raw counts into shares that are easy to grasp. This is why percentages are one of the most useful and widely understood tools in mathematics.