Mathematically, percentages are nearly identical to decimals, requiring minimal effort to convert: multiply the decimal by 100 and add the % sign to it. Conceptually, percentages are closer to fractions. Percentages are a way of showing the rate of something relative to 100. This allows you to compare the ratios between numbers, and can be a useful means of guessing how someone or something would be if it had a smaller or large sample size.

If one student correctly answers 9 problems out of 10, and a second student gets 18 out of 20, they have both scored 90%. A millionaire giving away $100,000 and a billionaire giving away $100,000,000 are giving equal amounts - 10% - relative to all their wealth. If you are allowed to take two out of eight identical pieces of pizza, you've gotten 25% of the pizza.