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%

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.