Topic Details (Notes format)

How to Calculate Percentage Increase or Decrease

Subject: Mathematics

Book: Maths Mastery

Percentage changes are ubiquitous in daily life, from price hikes to interest rate drops. To calculate a percentage increase, use the formula: [(New Value – Original Value) ÷ Original Value] × 100%. For instance, if a product’s price rose from ₹200 to ₹240, the increase is (240 – 200) = 40, and dividing by 200 yields 0.20, or a 20% increase. Conversely, percentage decrease follows the same formula but indicates a reduction in value. For example, if a ₹300 item drops to ₹225, the change is (225 – 300) = –75, and –75 ÷ 300 = –0.25, or a 25% decrease. Understanding percentage changes enables you to track stock performances, budget effectively, and compare year-on-year business growth. Frequent practice in real scenarios like monthly bills or commodity prices refines this essential skill.

Practice Questions

The perimeter of a rectangle is 50 cm, and its length is 15 cm. What is its width?

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What is the sum of all even numbers between 1 and 50?

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If x - y = 5 and x + y = 15, what is the value of x?

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If a right triangle has legs of 9 cm and 12 cm, what is the length of the hypotenuse?

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What is the value of x if log(x) + log(4) = log(32)?

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If a = 2 and b = 3, what is the value of (a^2 + b^2)?

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A train 150 m long passes a pole in 15 seconds. What is its speed?

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If a cylinder has a radius of 7 cm and height of 10 cm, what is its volume?

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If the sum of three consecutive integers is 72, what are the integers?

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What is the square root of 121?

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