Lesson 5: What is Percent?
Lesson 5: What Is Percent?
Percent as parts of 100, and how it connects to fractions and decimals.
Percent is a concept that is widely used in everyday life in a variety of situations.
“30% Discount”, “Yes, definitely, 100%” – are just some of the expressions that we encounter frequently.
It is important to understand what the above means and how it can be useful.
A percent is a number out of a 100. The term “percent” is derived from the Latin per centum, meaning “by the hundred”. In Ancient Rome, before the decimal system was invented, computations were often made in fractions which were multiples of 1/100 (or 0.01 if recorded as a decimal). Thus, computation with these fractions was the same as computing percentages.
100% represents a whole and can be split into parts: 25%, 40%, 78%, etc.
Percent was invented for convenience in order to easier represent fractions or decimals. Therefore, it can be converted into a fraction or a decimal.
For example, 1% = 0.01, because to convert a percent into a decimal, we need to divide the value by 100%.
We use percent to solve real world problems. For example, when we calculate the grade, we do so out of 100. Or when we survey people and show their preferences. We usually use a pie graph, split into parts, where one complete circle represents 100. We also use the concept when we discuss the improvement or when we measure something. In this lesson you will see how to do that.
Learn what the percentage of rain means in the weather forecast
Key ideas: What Is Percent?
Percent means “out of 100”. 25% = 25/100 = 0.25 = 1/4. Useful ones to remember: 50% = 1/2, 25% = 1/4, 75% = 3/4, 10% = 1/10.
To find a percent of a number, change the percent to a decimal and multiply. To write a part as a percent, divide the part by the whole and multiply by 100.
Worked examples
Example 1
Write 25% as a fraction and a decimal.
- 25% = 25/100 = 1/4 = 0.25
Example 2
Find 20% of 45.
- 20% = 0.20.
- 0.20 × 45 = 9
Example 3
Maya got 18 out of 24 on a quiz. What percent is that?
- 18 ÷ 24 = 0.75.
- 0.75 × 100 = 75%
Example 4
A $60 jacket is 30% off. What is the sale price?
- Discount: 0.30 × 60 = $18.
- Sale price: 60 − 18 = $42
Common mistakes
- Writing 5% as 0.5 (it is 0.05).
- Forgetting to subtract the discount from the original price.
Questions students ask
Can a percent be more than 100?
Yes. 150% means one and a half times the whole amount.
Grade 6 Percent Quiz
Check your understanding
Try the quiz for this lesson. You’ll see right away if each answer is correct.