Topic Details (Notes format)

How to Calculate the Percentage of a Number?

Subject: Mathematics

Book: Maths Mastery

Percentages are central to countless real-world applications—from calculating exam marks to determining discounts and interest rates. The general formula to find a percentage is: (Part / Whole) × 100%. However, if you already know the rate and the whole, use Percentage of a Number = (Rate ÷ 100) × Whole. For example, to calculate 20% of 150, convert 20% to 0.20, then multiply: 0.20 × 150 = 30. This concept is pivotal in areas like finance and data analysis, so practice by computing percentages for tips in restaurants, taxes on shopping bills, or proportionate contributions in group projects. Mastering this skill builds a strong foundation for advanced percentage operations such as percentage increase, decrease, and compound interest calculations.

Practice Questions

How many diagonals does a pentagon have?

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A square is inscribed in a circle with a radius of 5 cm. What is the area of the square?

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

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A sum of money triples itself in 12 years at simple interest. What is the rate of interest per annum?

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What is the HCF of 48 and 180?

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The LCM of 12 and 15 is:

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What is the sum of the interior angles of a hexagon?

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A man spends 75% of his income and saves Rs. 600. What is his total income?

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If a:b = 2:3 and b:c = 4:5, what is a:c?

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If log(100) = 2 and log(10) = 1, what is log(1000)?

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