Percentage
Percent change, successive percentages
Percentage is one of the most important topics in quantitative aptitude, forming the foundation for many other concepts like profit and loss, simple and compound interest, and data interpretation. A percentage represents a fraction with 100 as its denominator, making it a standardised way to compare quantities and express proportions.
Key formulas and rules
Key concepts
Basic Percentage Calculations
Converting fractions to percentages: multiply by 100. Converting percentages to fractions: divide by 100. Common conversions to remember: 1/2 = 50%, 1/3 ~= 33.33%, 1/4 = 25%, 1/5 = 20%, 1/6 ~= 16.67%, 1/8 = 12.5%, 1/10 = 10%, 1/12 ~= 8.33%, 1/16 = 6.25%, 1/20 = 5%. These quick conversions save time during calculations.
Percentage Change
Percentage increase or decrease is always calculated with respect to the original value. The formula is: (Change/Original) x 100. A common mistake is using the new value as the base. Remember: increase of 50% followed by decrease of 50% does NOT bring you back to the original value - it results in a net loss of 25%.