Quiz on Percentage of numbers for students. The percentage of a number or quantity reflects a proportion of that quantity or number on a hundred. The percentage sign is written as %. In problems like those in this quiz, you are asked to find the percentage of a number for example, find 20% of 100. In finding the percentage of numbers, you have to master skills in multiplying and simplifying fractions. Percentages are also commonly used to express quantities in various word problems in math especially when studying consumer math and problems related to money and interest rates. Children in 3rd, 4th, 5th and 6th grade will learn how to find the percentage of numbers.