Family Math Studio
Lesson 4.56.AT.4
Determine the Whole Given the Part and Percent
Find the whole when you know a part and its percent.
NameDate
Tonight's spark
A sweater tag says $42 after a sale. The sign says $42 is 60% of the regular price. What was the regular price?
Make a guess first: is the regular price more or less than $42?
Try it
Work it out on paper. Write one answer on each line.
10% of a number is 5. What is 100% of that number?
- A. 15
- B. 50
- C. 0.5
My answer
30 is 50% of a number. What is the number?
- A. 60
- B. 15
- C. 80
- D. 30
My answer
20 is 25% of a number. What is the number?
- A. 5
- B. 45
- C. 100
- D. 80
My answer
8 is 20% of the whole. What is 10% of the whole?
- A. 16
- B. 2
- C. 4
My answer
A shirt on sale costs $30, which is 50% of the original price. What was the original price?
- A. $15
- B. $60
- C. $80
- D. $30
My answer
18 is 30% of a number. What is the number?
- A. 60
- B. 5.4
- C. 48
- D. 540
My answer
Talk about it
When the whole is missing, why do we divide by the decimal percent instead of multiplying?
Home mission
Pick any price on a receipt. Say, "This is 50% of the full price." Can your student find the full price out loud? Then try 25%.
If we get stuck, ask
- Which amount is the part, and which is missing?
- What is that percent as a decimal?
- Should the whole be bigger or smaller than the part?