1. Percentages What are Percentages?

2. Percentages are measures out of a 100 Percentages

3. This grid is made up of 100 squares. We will use it to look at percentages.

4. In this case, fifty percent is shaded We write this as 50%

5. The following grids also show 50%.

6. These grids show 25%

7. And these show 10%

8. Can you name these percentages? 40%70% 5%64% ?? ??

9. Finding Simple Percentages of Numbers Percentages

10. Finding Fifty Percent (50%) 50% is the easiest percentage to find. All you have to do is halve your number.

11. Here is an example Find 50% of 70 70  35

12. Why do you divide by 2? The reason you divide by two is because there are two fifties in one hundred. 100  50 = 2

13. Find 50% of the following numbers. 40 50% of 40 =20 18 50% of 18 =9 130 50% of 130 = 65 15 50% of 15 =7.5

14. Finding Ten Percent (10%) 10% is an easy percentage to find. All you have to do is divide your number by ten.

15. Here is an example Find 10% of 40 40  4

16. Why do you divide by 10? The reason you divide by ten is because there are ten tens in one hundred. 100  10 = 10

17. Find 10% of the following numbers. 60 10% of 60 =6 150 10% of 150 =15 240 10% of 240 = 24 45 10% of 45 =4.5

18. Finding One Percent 1% is a little bit more difficult to find. To work out 1% you divide your number by one hundred.

19. Here is an example Find 1% of 120 120  1.2

20. Why do you divide by 100? The reason you divide by one hundred is because there are one hundred ones in one hundred. 100  100 = 1

21. Find 1% of the following numbers. 200 1% of 200 =2 1500 1% of 1500 =15 50 1% of 50 = 0.5 25 1% of 25 =0.25

22. Calculating Percentages without a Calculator. Percentages

23. 160 Finding various percentages of 160.

24. 160 Calculate 50% of 160 50% of 160  80

25. 160 50% of 160  80 25% is half of 50% 25%  40

26. 160 50% of 160  80 25%  40 75% is 50% + 25% 75%  120

27. 160 50% of 160  80 25%  40 75%  120 10% is 160  10 10%  16

28. 160 50% of 160  80 25%  40 75%  120 10%  16 20% is double 10% 20%  

29. 160 50% of 160  80 25%  40 75%  120 10%  16 20%   and 40% is double 20% 40%  64

30. 160 50% of 160  80 25%  40 75%  120 10%  16 20%   40%  64 1% is 160  100 1%  

31. 160 50% of 160  80 25%  40 75%  120 10%  16 20%   40%  64 1%   2% is double 1% 2%  3.2

32. 160 50% of 160  80 25%  40 75%  120 10%  16 20%   40%  64 1%   2%  3.2 and 9% is 9 x 1% 9%  14.4

33. 160 50% of 160  80 25%  40 75%  120 10%  16 40%  64 20%   1%   2%  3.2 9%  14.4 and 9% is 9 x 1%

34. Challenge Find 63% of 250.

35. 250 Start with 250

36. 250 50% of 250  125 Calculate 50% of 250

37. Calculate 10% of 250 250 50% of 250  125 10%  25

38. 60% = 50% + 10% 250 50% of 250  125 10%  25 60%  150 +

39. Calculate 1% of 250 250 50% of 250  125 10%  25 60%  150 + 1%  2.5

40. 3% is 3 x 1% 250 50% of 250  125 10%  25 60%  150 + 1%  2.5 3%  7.5

41. 63% is 60% + 3% 250 50% of 250  125 10%  25 60%  150 + 1%  2.5 3%  7.5 63%  157.5

42. and 9% is 9 x 1% 250 50% of 250  125 10%  25 1%  2.5 60%  150 3%  7.5 63%  157.5 +

43. Calculating Percentages with a Calculator. Percentages

44. The general method used here is to find 1%, then calculate the percentage you are looking for. For example, to find 21% of a number, you would divide it by 100, then multiply by 21.

45. Calculating 21% of 80 Use your calculator to find the answer to this problem. 80  100 x 21 = ?

46. Calculating 21% of 80 Use your calculator to find the answer to this problem. 80  100 x 21 = 16.8

47. Calculating 83% of 155 Use your calculator to find the answer to this problem. 155  100 x 83 = ?

48. Calculating 83% of 155 Use your calculator to find the answer to this problem. 155  100 x 83 = 128.65

49. Try these… 1. 18% of 60 2. 32% of 82 3. 77% of 144 4. 99% of 150 5. 52% of 52 6. 1.5% of 16 7. 41.7% of 88 = 10.8 = 26.24 = 110.88 = 148.5 = 527.04 = 24 = 36.08