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

What is the value of log₃(27)?

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The base of a triangle is 10 cm and its height is 6 cm. What is its area?

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

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The LCM of two numbers is 60, and their HCF is 5. If one of the numbers is 20, what is the other 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 a:b = 3:4 and b:c = 5:6, what is a:c?

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If x:y = 4:5 and y:z = 2:3, what is x:z?

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If x^2 - 6x + 9 = 0, what is the value of x?

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