Percentage Shortcuts for Aptitude Tests (with Solved Questions)

Learn 7 percentage shortcuts for placement aptitude tests with a fraction table, 15 solved questions and 10 practice questions with answers.

  Company-wise Interview Questions   Oct 4, 2026   20  Add to Reading List

Why Percentages Decide Your Aptitude Score

Percentage is the one quantitative topic you cannot skip. It appears directly in most placement aptitude tests, and it also sits inside other topics: profit and loss, discounts, simple and compound interest, data interpretation and even mixtures all use percentage calculations.

If you calculate percentages slowly, every one of those questions becomes slow. In a timed test like TCS NQT, Infosys, Wipro, Accenture or Capgemini, that lost time adds up across the whole section.

The good news: percentages follow a small set of patterns. Once you learn the fraction equivalents and seven shortcuts in this guide, most questions take under 30 seconds. Work through the 15 solved examples, then test yourself with the 10 practice questions at the end.

Percentage Basics and the Fraction Table

"Per cent" means "per hundred". So 35% is simply 35/100. To find a percentage of a number, multiply the number by the percentage and divide by 100.

x% of N = (x × N) ÷ 100

Percentage change always uses the original value as the base:

Percentage change = (New − Original) ÷ Original × 100

The biggest speed boost comes from memorising common fractions. Instead of calculating 12.5% of 480, you think “one-eighth of 480” and get 60 instantly.

FractionPercentageFractionPercentage
1/250%1/119.09%
1/333.33%1/128.33%
1/425%1/166.25%
1/520%1/205%
1/616.67%1/254%
1/714.29%3/475%
1/812.5%3/837.5%
1/911.11%5/862.5%
1/1010%7/887.5%

Tip: learn the table in pairs. If 1/8 is 12.5%, then 3/8 is 3 × 12.5 = 37.5% and 5/8 is 62.5%.

7 Percentage Shortcuts Every Fresher Should Know

Shortcut 1: Swap the Numbers

x% of y is always equal to y% of x. Use this when one direction is easier.

Example: 16% of 25 looks awkward, but 25% of 16 is simply one-quarter of 16 = 4.

Shortcut 2: Use Fractions, Not Decimals

Convert the percentage to a fraction from the table above, then divide.

Example: 37.5% of 640 = 3/8 × 640 = 3 × 80 = 240.

Shortcut 3: Successive Percentage Change

When a value changes by a% and then by b%, the net change is:

Net change = a + b + (a × b) ÷ 100

Use a minus sign for a decrease. Example: a salary rises 10% and then 20%. Net change = 10 + 20 + (10 × 20)/100 = 32% increase.

This single formula also solves successive discounts, area changes (length and breadth) and “increase then decrease” questions.

Shortcut 4: “More Than” vs “Less Than”

If A is r% more than B, then B is less than A by:

r ÷ (100 + r) × 100

If A is r% less than B, then B is more than A by:

r ÷ (100 − r) × 100

Example: A earns 25% more than B. B earns 25/125 × 100 = 20% less than A. The base changes, so the answer is not 25%.

Shortcut 5: Price Change and Consumption

If a price rises by r%, a family must cut consumption by r/(100 + r) × 100 to keep spending the same. If the price falls by r%, they can increase consumption by r/(100 − r) × 100. It is the same formula as Shortcut 4.

Example: petrol price rises 25%. Cut consumption by 25/125 × 100 = 20%.

Shortcut 6: Repeated Yearly Change

For population growth or machine depreciation at r% per year for n years:

Final = P × (1 ± r/100)n

Example: a town of 50,000 grows 10% a year. After 2 years: 50,000 × 1.1 × 1.1 = 60,500.

Shortcut 7: Work Backwards to the Original

If a number becomes F after an r% increase, the original is F × 100/(100 + r). After an r% decrease, it is F × 100/(100 − r).

Example: after a 20% increase, a price is ₹360. Original = 360 × 100/120 = ₹300. A common mistake is to take 20% of 360 and subtract it, which gives the wrong answer of ₹288.

15 Solved Percentage Questions for Placements

These questions follow the style seen in campus aptitude tests. Try each one for 30 seconds before reading the solution.

Q1. What is 87.5% of 320?

87.5% = 7/8. So 7/8 × 320 = 7 × 40. Answer: 280

Q2. A price is increased by 20% and then decreased by 20%. What is the net change?

Using a + b + ab/100: 20 − 20 + (20 × −20)/100 = −4. Not 0%. Answer: 4% decrease

Q3. A shop gives successive discounts of 20% and 10%. What single discount is equal to this?

−20 − 10 + (−20 × −10)/100 = −30 + 2 = −28. Answer: 28%

Q4. The length of a rectangle increases by 20% and the breadth decreases by 10%. What happens to the area?

20 − 10 + (20 × −10)/100 = 10 − 2 = 8. Answer: 8% increase

Q5. A’s salary is 50% more than B’s. By what percentage is B’s salary less than A’s?

50/150 × 100. Answer: 33.33%

Q6. The price of sugar rises by 20%. By how much should a family reduce consumption so that spending stays the same?

20/120 × 100. Answer: 16.67%

Q7. A machine worth ₹80,000 depreciates at 10% per year. What is its value after 2 years?

80,000 × 0.9 × 0.9. Answer: ₹64,800

Q8. A student needs 40% to pass. He scores 180 marks and fails by 20 marks. What are the maximum marks?

Pass marks = 180 + 20 = 200. Since 40% = 200, total = 200 × 100/40. Answer: 500

Q9. In an election between two candidates, the winner gets 60% of the votes and wins by 240 votes. How many votes were cast?

The loser gets 40%, so the margin is 20%. 20% = 240. Answer: 1,200 votes

Q10. 30% of a number is 72. What is 45% of the same number?

45% is 1.5 times 30%, so 72 × 1.5. No need to find the number first. Answer: 108

Q11. A fruit seller sells 40% of his apples and still has 420 left. How many did he have originally?

420 is 60% of the total. Total = 420 × 100/60. Answer: 700

Q12. A man spends 75% of his income. His income rises by 20% and his spending rises by 10%. By what percentage do his savings increase?

Take income = 100: spending 75, savings 25. New income 120, new spending 82.5, new savings 37.5. Increase = 12.5/25 × 100. Answer: 50%

Q13. After a 25% discount, a shirt sells for ₹1,800. What was the marked price?

1,800 × 100/75. Answer: ₹2,400

Q14. In a class, 70% passed English, 60% passed Maths and 40% passed both. What percentage failed both?

Passed at least one = 70 + 60 − 40 = 90%. Answer: 10%

Q15. A number is increased by 10% and then decreased by 10%. The result is 99. Find the number.

Net change = 10 − 10 − 1 = −1%. So 0.99 × N = 99. Answer: 100

10 Practice Questions (Answers Below)

Set a timer for 8 minutes and try all ten without a calculator.

  1. What is 62.5% of 480?
  2. A price rises by 30% and then falls by 30%. What is the net change?
  3. The price of rice falls by 20%. By what percentage can a family increase consumption without spending more?
  4. A is 20% less than B. By what percentage is B more than A?
  5. A town has 8,000 people and grows 5% every year. What is the population after 2 years?
  6. 12% of a number is 84. Find the number.
  7. One candidate scores 35% and fails by 30 marks. Another scores 45% and gets 20 marks more than the pass mark. Find the maximum marks.
  8. A value increases by 10% twice in a row. What is the total increase?
  9. The radius of a circle increases by 10%. By what percentage does its area increase?
  10. What is 25% of 30% of 400?

Answers

QAnswerQuick Method
13005/8 × 480
29% decrease30 − 30 − 900/100
325%20/80 × 100
425%20/80 × 100
58,8208,000 × 1.05 × 1.05
670084 × 100/12
750010% = 30 + 20 = 50
821%10 + 10 + 100/100
921%Area uses r², so 10 + 10 + 1
10301/4 × 3/10 × 400

Scored 8 or more? Move on to Profit and Loss Shortcuts, which builds directly on these ideas. Scored less? Re-read Shortcuts 3 and 7, which cover most mistakes.

Common Mistakes and How to Avoid Them

Most wrong answers in percentage questions come from four habits:

  • Using the wrong base. “A is 25% more than B” and “B is 25% less than A” are different statements. Always ask: percentage of what?
  • Adding successive changes. A 10% rise followed by a 10% rise is 21%, not 20%. Always use a + b + ab/100.
  • Subtracting from the final value. To undo a 20% increase, divide by 1.2. Do not subtract 20% of the final number.
  • Calculating too early. In Q10 above, the number itself was never needed. Look for a ratio between the given and asked percentages before you calculate.

How to Practise for the Exam

Spend one week on this topic before moving on. A simple plan:

  1. Days 1–2: Memorise the fraction table until you can recall any value in under 2 seconds.
  2. Days 3–4: Solve 20 questions a day using only the seven shortcuts.
  3. Days 5–6: Take timed sets of 10 questions in 8 minutes.
  4. Day 7: Mix percentage questions with profit and loss and interest questions.

In the actual test, skip any percentage question that takes more than 60 seconds and come back to it later. Check the latest section pattern for your target company on its official careers page, as patterns change between hiring seasons. Our TCS Aptitude Test Pattern guide is a good starting point.

Frequently Asked Questions

What is the fastest way to calculate percentages in aptitude tests?

Convert the percentage to a fraction (12.5% = 1/8, 33.33% = 1/3) and divide. This is faster than multiplying decimals.

What is the formula for successive percentage change?

Net change = a + b + (a × b)/100. Use negative values for decreases.

Why is a 20% rise followed by a 20% fall not zero?

The fall is calculated on a larger number, so the net result is a 4% decrease.

How many percentage questions come in placement tests?

It varies by company and year. Percentage logic also appears inside profit and loss, interest and data interpretation questions, so it affects more of your score than the direct questions alone.

Can I use a calculator in placement aptitude tests?

Some online tests provide an on-screen calculator and many do not. Check the instructions for your specific test, and practise without one either way.

Final Word

Percentages reward memory and pattern recognition more than heavy calculation. Learn the fraction table, master the seven shortcuts, and solve a timed set every day for a week.

Next, continue your aptitude preparation with Profit and Loss Shortcuts, Time Speed and Distance Formulas and our complete Aptitude Test Preparation Tips guide.

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