This document provides four rules for performing operations on percentages: 1) To multiply a number by a percentage, convert the percentage to a decimal and multiply. 2) To multiply by a fraction of 1%, first get 1% of the number and multiply the result by the fraction. 3) To multiply by an aliquot part, first convert the percentage to a fraction then multiply. 4) To divide a number by a percentage, first convert the percentage to a decimal or fraction before dividing. Examples are provided to demonstrate each rule.

2. Four Fundamental of Operation

3. Operations on Percent By: Angel A. Abrilla Jr. Student Teacher

4. Rule #1 To multiply a number by any percent: convert the percent to its equivalent decimal number, then multiply it to the given. Here are the examples 1.) 25% of 80 = 0.25 x 80=20 2.) 65% of 400 = 0.65 x 400=260

5. Rule #2 To multiply by a fraction of 1%, first get one percent of the number and multiply this product by the fraction of the percent given. Here’s the example: A. 1/3% of 300 means 1/3 of 1% of 300 1/3 of (1% of 300) = 1/3 x 3 =1

6. Another example: 1\5% of 4500 means 1/5 of (1% of 4500) 1/5 of 45 =9

7. Rule #3 To multiply a number by any of these aliquot parts, it is easier to convert the percent first to the fractional equivalent then multiply. Here’s the example: A. 12 ½ % of P5600 =1/8 x P5600 = P700

8. Another example: B. 83 1/3 % of P420 = 5/6 x P420 = P350

9. Rule #4 To divide a number by a percent, convert the percent to its decimal or fractional equivalent before doing the division Here’s the given example: A. 18 is 36% of what number? Solution: 18/36% = 18/0.36 =1800/36 = 50

10. Another example: 48 is 37 ½ % of what number? Solution: 48/37 ½% = 48/ 3/8 = 48 x 8/3 = 128 48/37 ½% = 48/ 37.5% = 48/0.375 = 48000/375 = 128 Or

11. Answer the following given questions. 1.) 50% of 5600 2.) 1% of 970 3.) What number of 50% is 2? 4.) What number of 10% is 15? 5.) 18 is what number of 25%

12. Answers: 1.) ½ x 5600 = 280 2.) 0.01 x 970 = 9.7 3.) 2/.50 = 200/50 = 4 4.) 15/.10 = 1500/10 = 150 5.) 18/25% = 18/0.25 = 1800/25 =72

13. How to multiply a number by any percent? Convert the percent to its equivalent decimal number, then multiply.

14. How about multiplying a number by any of the aliquot parts? Convert the percent first to the fractional equivalent then multiply.

15. If there are sales in the mall, is it good to buy a discounted item than the original price?

16. Find each number using a fraction for the percent. 1. 10% of 500 2. 20% of 60 3. 50% of 125 4. 50% of 540 5. 12 ½ % of 36

17. Answers: 1. 10/100 = 1/10 x 500 = 50 2. 20/100 = 1/5 x 60 = 12 3. 50/100 = ½ x 125 = 62/ ½ or 62.5 4. 50/100 = ½ x 540 = 270 5. 12.5/100 = 1/8 x 36 = 4/ ½ or 4.5

18. Get a piece of paper, find the total cost , including tax. 1. A hamburger meal costs P40. The sales tax is 4%. 2. A calculator sells for P850. The sales tax is 6%. 3. Jack bought 3 diskettes at P35 each, s 5% sales tax. 4. A record sells for P48. The sales tax is 7%.

19. Answers: 1.) Total cost: 38.4 Tax: 1.6 2.) Total cost: 799 Tax: 51 3.) Total cost: 105 Tax: 5.25 4.) Total cost: 44.64 Tax: 3.36

20. Assignment: Answer page 226, guided practice (B only) on Integrative Mathematics 6.