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Learning about

Learning about. Using Inverse Operations for finding the original price after a percentage increase or decrease. To find a percentage of a number, you. Divide the percent by 100. And multiply by the number. Notice that  100 changes the % to a decimal. 12% of 40 =. 12  100

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Learning about

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  1. Learning about Using Inverse Operations for finding the original price after a percentage increase or decrease

  2. To find a percentage of a number, you.. Divide the percent by 100 And multiply by the number Notice that  100 changes the % to a decimal 12% of 40 = 12  100 (= 0.12) X 40 = 4.8

  3. The increased amount is (100 + 12)% of the original If you wanted to increase 40 by 12% Find 12% of 40 and then add this answer to 40 We already know that 12% of 40 is 4.8 or Notice that 112 100 changes the % to a decimal which is 1.12 112% of 40 = 4.8 + 40 112  100 (= 1.12) X 40 = 44.8

  4. If you wanted to decrease £125 by 23% The reduced amount is (100 - 23)% of the original Find 23% of 125 and then subtract this answer from 125 23  100 x 125 = 28.75 £125 - £28.75 = £96.25 Notice that 77 100 changes the % to a decimal which is 0.77 or 77  100 (= 0.77) X 125 = £96.25

  5. To increase by a percentage Input Output 40 X 0.12 4.8 40 44.8 X 1.12

  6. Using inverse operations! Insurance costs have increased by 12% The cost after the increase is £44.80 Output Input ? 44.8 X 1.12 What was the cost before the increase? It cost £40 before the increase  1.12 40 44.8

  7. Using inverse operations! Insurance costs have increased by 23% The cost after the increase is £88.56 Output Input ? X 1.23 88.56 What was the cost before the increase? It cost £72 before the increase 72  1.23 88.56

  8. To decrease by a percentage Input Output 125 28.75 X 0.23 What is £125 minus £28.75? 96.25 125 X 0.77

  9. The sale price is (100-23)% of the original price Using inverse operations! In a sale stock is reduced by 23% The sale price of a suit is £96.25 Input Output ? 96.25 X 0.77 What was the cost before the increase? It cost £125 before the sale 125  0.77 96.25

  10. The sale price is (100-18)% of the original price Round to 2dp for money! Using inverse operations! In a sale stock is reduced by 18% The sale price of a suit is £96.25 Output Input ? X 0.82 96.25 What was the cost before the increase? It cost £117.38 before the sale 117.38  0.82 96.25

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