1. Do not use a calculator
for the following!!

2. The 10% Rule
The 10% Rule
The 10% Rule
What is an easy way
to find 10% of a number?

3. How do you find10% of 20?
Where's the
decimal point? 20
Right there!

4. Move the decimal point
1 place to the left 20

5. That makes10% of 20
equal to 2

6. .
What is 10% of 7
700 .7
.07
70?

7. What is 10% of 70? 7 70

8. .
What is 10% of .3 30
.03 3
30?

9. What is 10% of 30? 3 30

10. .
What is 10% of
1.2 12
.12
.012
120?

11. What is 10% of 120?
120 12

12. .
What is 10% of
4.5
.45
450
.045
45?

13. What is 10% of 45? 45

14. .
What is 10% of
3.50
.35
350
.035
$3.50

15. What is 10% of $3.50
or 35 c
$35
$350

16. .
What is 5% of
.50 .5 5 50
100?

17. % means "out of 100" The answer is 5 therefore, 5% means
What is 5% of 100?
% means
"out of 100"
The answer is 5
therefore, 5% means
"5 out of 100"

18. 10% of 100 = 10 2 2
The "total" is the same
5% of 100 = 5

19. .
What is 5% of 4 6 2 .4
40?

20. What is 5% of 40?
10% of 40 is
of 40 is 4 2 2 2 5%

21. .
What is 5% of 4 6 8 16
80?

22. What is 5% of 80? 80 4 2

23. .
What is 5% of 4 2 8 16
160?

24. What is 5% of 160?
160 2 8

25. .
What is 15% of 2 6 8 10
40?
10% of 40 = 4
+ 5% of 40 = 2
15% of 40 = 6

26. .
What is 15% of 12 60 18
100
120?
10% of 120 = 12
+ 5% of 120 = 6
15% of 120 = 18

27. .
What is 20% of 12 60 18
100
90?
10% of 90 = 9
+ 10% of 90 = 9
20% of 90 = 18

28. .
What is 30% of 30 60 45 90
150?
10% of 150 = 15
+ 10% of 150 = 15
30% of 150 = 45

29. .
What is 25% of 18 6 15 12
60?
10% of 60 = 6
+ 5% of 60 = 3
25% of 60 = 15