Unit 4 · Standard 6.RP.3c
Find the Percent of a Number
Key Vocabulary Level 1 support
Picture first, then the word, then a plain-language meaning. Say each word out loud.
30% means 30 out of 100
Percent
A way to compare a number to 100, shown with the % sign.
In '25% of 80,' the base is 80
Base
The whole amount you take a percent of.
25% of 80 = 20; the part is 20
Part
The piece you get when you take a percent of a number.
part = percent × base
Equation
A math sentence with an equal sign showing both sides are the same.
$40 shirt at 25% off: discount = $10
Discount
Money taken off the first price to make it cheaper.
Key Ideas & Notes
- It's Discount Day at the arcade!
- Different games are offering percent-off deals on ticket prices.
- The claw machine is 25% off its usual 60-ticket price, and the racing game is 40% off 80 tickets.
- You need to calculate the discounts to figure out how many tickets each game actually costs!
- Find the percent of each number. Use the equation: Part = Percent × Base. Convert the percent to a decimal first.
Think About It
- What information do you need to find the discount amount?
- How is finding 25% of 60 different from finding 40% of 80?
- Is there more than one way to find a percent of a number?
My Notes
Guided Examples
Example 1
What is 20% of 150?
Solution: 20% = 0.20. Multiply: 0.20 × 150 = 30.
Answer: A. 30
Example 2
What is 50% of 84?
Solution: 50% = 0.50. Multiply: 0.50 × 84 = 42. (Or simply divide by 2: 84 ÷ 2 = 42.)
Answer: A. 42
Example 3
What is 10% of 320?
Solution: 10% = 0.10. Multiply: 0.10 × 320 = 32. (Or move the decimal one place left.)
Answer: A. 32
Write About the Math The Writing Revolution
I can explain my steps using the words percent, base, part, and equation.
1. Kernel Sentence subject + verb
Model: Percent is a way to compare a number to 100, shown with the % sign.Porcentaje es una manera de comparar un número con 100, con el signo %.
Write a kernel sentence about percent. Use a subject and a verb.Escribe una oración base sobre porcentaje. Usa un sujeto y un verbo.
2. Sentence Expansion because · but · so
Kernel: Percent matters in mathPorcentaje importa en matemáticas
Expand the kernel three ways. Add a reason, a contrast, and a result.
Percent matters in math because ___.Porcentaje importa en matemáticas porque ___.
Percent matters in math, but ___.Porcentaje importa en matemáticas, pero ___.
Percent matters in math, so ___.Porcentaje importa en matemáticas, entonces ___.
3. Sentence Types 4 ways to write a math idea
Tell one true fact about percent.Di un hecho verdadero sobre percent.
Percent ___.
Ask a question about percent.Haz una pregunta sobre percent.
How does ___ ?¿Cómo ___ ?
Show excitement about percent.Muestra entusiasmo sobre percent.
Wow, ___ !¡Guau, ___ !
Tell a partner what to do with percent.Dile a un compañero qué hacer con percent.
First, ___ .Primero, ___ .
4. Explain Your Reasoning use a sentence starter
I changed ___% into ___.Cambié ___% a ___.
Then I multiplied by ___.Luego multipliqué por ___.
I would do this to find ___.Haría esto para hallar ___.
Try It
Solve on your own. Check the answer key when you are done.
1. An arcade prize costs 240 tickets. If you have a coupon for 15% off, how many tickets do you save?
- 36 tickets
- 24 tickets
- 15 tickets
- 204 tickets
2. A student scored 72 out of 90 on a test. What percent did they score?
- 80%
- 72%
- 75%
- 90%
Stretch Your Thinking Level 2 enrichment
Challenge task — explain your reasoning in full sentences.
A class has 32 students. 25% are in the math club, 50% are in the reading club, and 12.5% are in both. How many students are in each group? Can the total of all three groups be more than 32? Explain why or why not.
Sentence starter: There are ___ in math club, ___ in reading club, and ___ in both. The total ___ be more than 32 because ___.
Reflect — Exit Ticket
What is 45% of 360?
- 162
- 145
- 180
- 126
Answer Key & Teacher Guide
- Try It 1: A. 36 tickets — 15% of 240 = 0.15 × 240 = 36 tickets saved.
- Try It 2: A. 80% — 72 ÷ 90 = 0.80 = 80%.
- Exit Ticket: A. 162 — 45% = 0.45. Multiply: 0.45 × 360 = 162.
Writing (TWR) — what to look for
- Kernel sentence: A complete sentence needs a subject and a verb. Example: Percent is a way to compare a number to 100, shown with the % sign.
- Expansion: because gives a reason, but shows a contrast or exception, so shows a result. Answers vary; each must keep the kernel idea and add the correct kind of detail.
- Sentence types: Statement ends with a period, question with "?", exclamation with "!", and a command starts with an action verb (a "bossy" verb).