This document provides an introduction to percentages, including where they come from, what they represent, common usages, and why they are useful. It explains that percentages represent a quantity out of 100 to allow for easy comparison. Examples show how to convert percentages to fractions and decimals. Common percentages discussed include discounts, sales taxes, and exam scores. The key reason given for using percentages is that they allow for comparison of different quantities on the same scale from 0% to 100%.

1. Percentage Basics & Introduction
- By Kari Knisely

2. What you will learn…
 Where percents come from
 What percents are
 What percents look like
 Common percentages used in everyday life
 Why we use percents

3. Where Percents Come From
 Italian roots most commonly assumed

4. Where did percents come from?
Merriam-Webster – click here for more information
Encyclopedia/Merriam-Webster – click here for more information
Merriam-Webster Dictionary. Retrieved on March, 24 2012 from http://www.merriam-
webster.com/dictionary/percent

5. What Percents are & Basic Info
 Converts any quantity into a part of 100 to easily compare

6. What is a Percent?
Per cent
Per 100
÷ 100
%= parts per 100

7. Percents as Fractions
Steps
2.Percentage number becomes numerator
3.Denominator becomes 100
4.Remove the percent sign
5.Simplify
75 75 25 3
75 %
100 100 25 4
75 % 3
4

8. Percents as Decimals
Steps
2.Move decimal 2 places left
3.Remove the percent sign
4.Re-write decimal
75 % 75.0 % 75.0 %
  0.75

9. Is more than 100% possible?
200%

10. Is more than 100% possible?
175%
75%

11. What does a percent look like?
%

12. What does a percent look like?

13. What does a percent look like?
40 Test Questions = 100% = 1.0

14. What does a percent look like?
40 Test Questions = 100% = 1.0
50% 50%
20 ?s 20 ?s
0.50 0.50

15. What does a percent look like?
40 Test Questions = 100% = 1.0
25% 25%
10 ?s 10 ?s
0.25 0.25
25% 25%
10 ?s 10 ?s
0.25 0.25

16. What does a percent look like?
40 Test Questions = 100% = 1.0
12.5% 12.5%
5 ?s 5 ?s
12.5% 0.125 0.125 12.5%
5 ?s 5 ?s
0.125 0.125
12.5% 12.5%
5 ?s 5 ?s
0.125 12.5% 12.5% 0.125
5 ?s 5 ?s
0.125 0.125

17. Common Percentage Types
 Discounts & Sales
 Tips
 Taxes

18. Common Percentage Types

19. Common Percentage Types
Calculate

20. Common Percentage Types
Calculate

21. Common Percentage Types

22. Common Percentage Types
Calculate

23. Common Percentage Types
Calculate

24. Common Percentage Types

25. Common Percentage Types
Original $24.99
Discount - 7.50
Sale Price $17.49
FL Tax Rate 6% = ?
Calculate

26. Common Percentage Types
Original $24.99
Discount - 7.50
Sale Price $17.49
FL Tax Rate 6% = ?
Calculate

27. Why do we use percents?
 Compare different quantities

28. Why do we use percents?
Brad’s Math Test Kim’s Science Test
45 questions correct 52 questions correct
IF 50 questions total IF 60 questions total

29. Why do we use percents?
45 ?s
If 50 total ?s
0 ?s 12.5 ?s 25 ?s 37.5 ?s 50 ?s
0% 25% 50% 75% 100%
≈ 90%
Brad’s Math Test
45 questions correct
IF 50 questions total

30. Why do we use percents?
Kim’s Science Test
52 questions correct
IF 60 questions total
52 ?s
If 60 total ?s
o ?s 15 ?s 30 ?s 45 ?s 60 ?s
0% 25% 50% 75% 100%
≈ 87%

31. Why do we use percents?
45 ?s
If 50 total ?s
0 ?s 12.5 ?s 25 ?s 37.5 ?s 50 ?s
0% 25% 50% 75% 100%
≈ 90%
52 ?s
If 60 total ?s
o ?s 15 ?s 30 ?s 45 ?s 60 ?s
0% 25% 50% 75% 100%
≈ 87%

32. Why do we use percents?
Brad’s Math Test Kim’s Science Test
45 questions correct 52 questions correct
IF 50 questions total IF 60 questions total
= 90% = 87%

33. Why do we use percents?
Brad’s Math Test Kim’s Science Test
16 questions correct 16 questions correct
IF 20 questions total IF 24 questions total

34. Why do we use percents?
16 ?s If 20 total ?s
0 ?s 5 ?s 10 ?s 15 ?s 20 ?s
0% 25% 50% 75% 100%
≈ 80%
Brad’s Math Test
16 questions correct
IF 20 questions total

35. Why do we use percents?
Kim’s Science Test
16 questions correct
IF 24 questions total
16 ?s If 24 total ?s
o ?s 6 ?s 12 ?s 18 ?s 24 ?s
0% 25% 50% 75% 100%
≈ 65%

36. Why do we use percents?
16 ?s If 20 total ?s
0 ?s 5 ?s 10 ?s 15 ?s 20 ?s
0% 25% 50% 75% 100%
≈ 80%
16 ?s If 24 total ?s
o ?s 6 ?s 12 ?s 18 ?s 24 ?s
0% 25% 50% 75% 100%
≈ 65%

37. Why do we use percents?
Brad’s Math Test Kim’s Science Test
16 questions correct 16 questions correct
IF 20 questions total IF 24 questions total
≈ 80% ≈ 65%

38. What you have learned…
 Where percents come from
 What percents are
 What percents look like
 Common percentages used in everyday life
 Why we use percents

39. Works Cited
 All images retrieved from Google images

40. Why do we use percents?
16 ?s If 20 total ?s
0 ?s 5 ?s 10 ?s 15 ?s 20 ?s
0% 25% 50% 75% 100%
≈ 80%
16 ?s If 24 total ?s
o ?s 6 ?s 12 ?s 18 ?s 24 ?s
0% 25% 50% 75% 100%
≈ 65%

41. Why do we use percents?
45 ?s
If 50 total ?s
0 ?s 12.5 ?s 25 ?s 37.5 ?s 50 ?s
0% 25% 50% 75% 100%
≈ 90%
52 ?s
If 60 total ?s
o ?s 15 ?s 30 ?s 45 ?s 60 ?s
0% 25% 50% 75% 100%
≈ 87%