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

What is the HCF of 48 and 180?

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If the angles of a triangle are in the ratio 2:3:4, what is the measure of the largest angle?

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The LCM of 12 and 15 is:

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If a rectangle has a length of 10 cm and a width of 6 cm, what is its perimeter?

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If a square has a perimeter of 64 cm, what is its area?

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If the average of five consecutive odd numbers is 25, what is the largest number?

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If a + b = 10 and ab = 21, what is the value of a^2 + b^2?

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If the perimeter of a square is 36 cm, what is the length of its diagonal?

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What is the LCM of 15 and 20?

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What is the sum of the first 20 odd numbers?

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