How percentages work
A percentage is a number out of 100: 45% means 45 of every 100. To find a percentage of a number, multiply the number by the percentage and divide by 100. To turn a part into a percentage, divide it by the whole and multiply by 100.
Percentage of a number = number × percentage ÷ 100 Part as a percentage = part ÷ whole × 100
Your marks as a percentage
Divide the marks you scored by the maximum marks and multiply by 100: 425 out of 500 is 425 ÷ 500 × 100 = 85%. For several subjects, add up the marks scored and the maximum marks first, then divide one by the other.
Percentage increase and decrease
A change is measured against the starting number: subtract the old number from the new one, divide by the old number and multiply by 100. A fee that goes from ₹200 to ₹250 has risen by 50 ÷ 200 × 100 = 25%. Going back from ₹250 to ₹200 is a fall of 20%, not 25%, because the starting number is now ₹250.
Change = (new − old) ÷ old × 100