Percentage increase/decrease = (Change in value)/(Original value) × 100%

 

Note: Original value is in denominator

 

Suppose I have 100 rupees. And Harshit gave me Rs 20. What is the percentage increase in money I have?

 

Original amount = Rs 100

Amount after increase = Rs (100 + 20)

     = Rs 120

 

Change in value = 120 − 100

    = 20

 

Thus,

  Percentage increase = (Change in value)/(Original amount) × 100%

     = 20/100 × 100%

                                    = 20%

 

Suppose I have 100 rupees. And, Harshit took Rs 25 from me. What is the percentage decrease?

 

Original amount = Rs 100

Amount after decrease = Rs 100 − 25

= Rs 75

 

Change in value = 100 − 75

    = 25

 

Thus,

  Percentage decreased = (Change in value)/(Original amount) × 100%

 = 25/100 × 100%

 = 25%

  1. Chapter 8 Class 8 Comparing Quantities
  2. Concept wise
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.