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

A triangle has angles 60°, 60°, and 60°. What type of triangle is it?

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The ratio of two numbers is 3:5, and their sum is 64. What are the numbers?

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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 x^2 - 5x + 6 = 0, what are the roots?

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

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What is the length of the diagonal of a square with a side length of 7 cm?

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The probability of getting an even number when rolling a die is:

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If sin(A) = 3/5 and cos(B) = 5/13, where A and B are acute angles, what is sin(A+B)?

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If the sum of the squares of two consecutive positive integers is 365, what are the integers?

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If a cone has a radius of 5 cm and a height of 12 cm, what is its slant height?

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