20% is 1/5 To find 20% of a number divide by 5

(Tip/time-saver: or divide by 10 and double)

40% = 2/5, 60% = 3/5; 80% = 4/5; 100% = 5/5.

By Jim Olsen, W.I.U.#P9

15 10

5

75

85

45

25

65

35

955

505

20% 120%40% 60% 80% 100% 140% 180%160% 200%0%

Find the percent1. 10 makes out of 50 attempts:

2. 32 yes votes on 40 ballots:

3. 1,200 adults out of 2,000 members:

10 120%

50 5

32 480%

40 5

1200 12 360%

2000 20 5

If the number is easily divisible by 5: To find 20% of a number divide by 5

Examples:

20% of 30 is 6

20% of 45 is 9

If the number is not easily divisible by 5: Divide by 10 and double

Examples:

20% of 31 is 6.2

20% of 230 is 46

Recall the strategy:To find A% of BYou can change the percent to a fraction,Find B divided by the bottom, thenMultiply by the top.

Find 60% of 35

3 4560% of 45 45 3 9 3 27

5 5

Examples:

1. If the total revenue is $500 and 40% is profit, how much is profit?

2. If to make 30 tons cement mixture we 60% sand, how much sand do we need?

3. This year’s sales are 120% of last year’s sales. If last year we sold $4,500, what are sales this year?

4. If commission is 20% and the sale was $2,340, what is the commission?

240% of 500 500 $200

5

60% of 30 18 tons

6 4500120% of 4500 = of 4500 6 900 6 $5,400

5 5

2340 234 $468

Closing Notes Remember

20% is 1/5 To find 20% of a number divide by 5

(or divide by 10 and double)40% = 2/5, 60% = 3/5; 80% = 4/5

#P9