1. Understanding Percent

2. What does per cent mean? Per means one.
Cent is one penny out of a dollar.

3. A percent is a portion of a whole.
How many parts do you need to start with ?
You need 100 parts.

4. Let’s talk about money How many pennies are in a dollar?
There are 100 pennies in a dollar.

6. Since there are 100 pennies, I could easily find any percent.
25% would be 25 out of 100 pennies.
That would be 25₵. You can also write this as 0.25 or .25

7. 12% would be 12 out of 100 pennies.
That would be 12₵. You can also write this as 0.12 or .12

8. Let’s think about 2.00.
To make 100 equal groups, how many pennies would be in each group?

9. There would be 2 pennies in each group.

10. So if I wanted to find 18% of 2, that would be 18 boxes.
Since there are 2 pennies in each box, it would be a total of 36 pennies or 36₵.
You can also write this as 0.36 or just .36

11. What if you had $5.00? How many pennies could be in each box?

12. All those pennies won’t fit in my picture, so let’s use tally marks.

13. Each mark stands for 1 penny.

14. So there is 5₵ in each box.
We can write that as .05 per box.

15. So if I wanted to know 37% of $5.00,
I would have to add = ?

16. Can you think if an easier way?
= ?

17. Multiply!!! 37 boxes X .05 per box 185
There are 2 digits after the decimal, so there needs to be 2 digits after the decimal in your answer.
185. = 1.85

18. Do you notice any patterns?
Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
Do you notice any patterns?

19. Who can tell me how many pennies if I had….
Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
Who can tell me how many pennies if I had….

20. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20

21. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20

22. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2

23. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87

24. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87

25. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99

26. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99 99

27. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99 99
.99

28. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99 99
.99
$112

29. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99 99
.99
$112
112

30. Total
# of pennies in each box
Written as a decimal
$1.00 1
.01
$2.00 2
.02
$5.00 5
.05
$20 20
.20 or .2
$87 87
.87
$99 99
.99
$112
112
1.12

31. When you are calculating percent, you are
Splitting the whole into 100 equal parts (moving the decimal 2 places to the left)
Then adding (or multiplying) the required number of parts out of 100
17% of 63
Split 63 into 100 equal parts by moving the decimal .63
You need 17 out of 100 parts. Each part is worth .63
17 ● .63 = 10.71
17% of 63 is 10.71

32. The communitive rule of multiplication allows us write the percent as a decimal instead.
Write 17% as a decimal (move the decimal 2 spaces to the left) .17
.17 ● 63 = 10.71
17% of 63 is 10.71

33. One last example: 84% of 126
84 ● 1.26 = OR
.84 ● 126 =