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

If the radius of a circle is 7 cm, what is its circumference?

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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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What is the greatest common divisor (GCD) of 36 and 48?

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What is the cube root of 729?

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

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

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If a:b = 5:7 and b:c = 6:11, what is a:c?

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How many diagonals does a pentagon have?

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