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

View Question

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

View Question

What is the value of x if log(x) + log(4) = log(32)?

View Question

What is the value of x if 3x + 7 = 16?

View Question

If the perimeter of a square is 40 cm, what is the area of the square?

View Question

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

View Question

If a person can type 45 words per minute, how many words can they type in 2 hours?

View Question

A car covers a distance of 150 km in 2.5 hours. What is its average speed?

View Question

What is the HCF of 48 and 180?

View Question

A sum triples in 20 years at simple interest. What is the rate of interest per annum?

View Question