GMAT Percentage Tricks: Master Essential Tips for Success

Key Takeaways:

• Key Percentage Formulas: Learn essential formulas that are frequently used in GMAT percentage problems.
• Shortcuts for Quick Calculations: Discover tricks that help you calculate percentages faster, even without a calculator.
• Common Mistakes to Avoid: Identify and prevent common errors students often make with percentage questions on the GMAT.
• Practice Questions for Mastery: Strengthen your skills with a set of GMAT-style percentage questions designed to improve your accuracy.
• Time-Saving Tips for Exam Day: Maximize your efficiency by using these quick calculation strategies for the quantitative section.

Mastering percentages is crucial for acing the GMAT quantitative section, where questions often challenge your speed and accuracy. Knowing a few key percentage tricks can help you solve problems more efficiently, allowing you to focus on tougher questions during the exam. In this blog, we’ll explore smart strategies and shortcuts to handle percentage-related questions with confidence, saving you precious time on test day.

Why Percentage Questions are Important in the GMAT

Percentage questions form a crucial part of the GMAT quantitative section, both in the problem-solving and data sufficiency questions. Understanding the concept of percentages is essential because it shows up frequently in various forms, from simple percentage increases or decreases to more complex multi-step problems involving percentages.

Percentages are used to measure relative change, such as calculating profit, loss, discounts, or interest. For example, if you are asked to find what 25% of 200 is, you would calculate 0.25 × 200 = 50. Being comfortable with these types of calculations will help you save time during the exam.

Mastering percentages also allows you to handle data sufficiency questions more effectively. In these questions, you must determine whether the information provided is enough to solve the problem, and percentages are often used as the key detail.

Key GMAT Percentage Tricks You Need to Know

To excel in GMAT percentage questions, you need to be familiar with several tricks that can save you time and help avoid errors. Below are some key tricks that are widely used:

1. Converting Fractions to Percentages Efficiently

One of the most effective tricks is converting common fractions to percentages quickly. For example, knowing that 1/4 = 25% or 1/3 ≈ 33.33% can speed up problem-solving. You don't need to calculate these from scratch each time.

2. Percentage Increase and Decrease Questions

When solving these questions, use the formula:

Percentage Change = ((New Value - Original Value) / Original Value) × 100

For instance, if the price of a product increases from $80 to $100, the percentage increase is:

(100 - 80) / 80 × 100 = 25%

Practicing with similar problems will help you recognize patterns and solve them faster during the test.

3. Compound Percentages

For more complex problems involving successive percentage changes, the best approach is to break the problem into manageable parts. For instance, a 10% increase followed by a 20% decrease isn't the same as a 30% decrease. Instead, you apply the changes one by one to get the final result.

How to Approach Percentage Word Problems in GMAT

Percentage word problems are commonly tested on the GMAT and often appear in both the Problem Solving and Data Sufficiency sections. These problems typically involve real-world scenarios like price changes, population growth, discounts, and interest rates. The key to solving percentage word problems is breaking them down into smaller, manageable steps.

Step-by-Step Approach to Solving Percentage-Based Word Problems:

1. Identify the given values
   First, determine the original value and the percentage in the question. For instance, if the question asks, “A store offers a 20% discount on a product that costs $50, what is the final price?”
   • The original price is $50.
   • The percentage discount is 20%.
2. Apply the percentage change
   Use the percentage change formula:

     Final Price = Original Price - (Percentage × Original Price)
     

   In the above example:

     Final Price = 50 - (0.20 × 50) = 50 - 10 = 40
     

   The final price is $40.
3. Interpret the result
   After calculating, it’s essential to understand what the result represents in the context of the problem.

Common Mistakes to Avoid in Percentage Calculations:

1. Forgetting to adjust the base value
   Always ensure you’re calculating percentages based on the correct base value. In compound percentage questions, the base changes after each percentage is applied.
2. Misinterpreting percentage decreases
   When applying a percentage decrease, students often subtract from 100% instead of applying the percentage correctly. For instance, if a price drops by 30%, you calculate the new price based on the remaining 70%, not by subtracting 30 from 100.

Advanced GMAT Percentage Tips for High-Scorers

Tackling Hard GMAT Percentage Questions:

1. Break the Problem into Smaller Parts
   Many challenging percentage questions combine multiple steps, such as finding a percentage change followed by another calculation. For example, if a company’s revenue increases by 25% one year and 10% the next, calculating the overall change is not simply adding the two percentages. Instead:

     Start with an original revenue of $100.
     After a 25% increase: 100 + 25% × 100 = 125
     After a 10% increase: 125 + 10% × 125 = 137.5
     

   The overall increase is $37.5, which is a 37.5% increase over two years.
2. Utilize Approximation Techniques for Speed
   Some GMAT questions require fast calculations, and approximation can save time. For instance, if a question asks you to calculate 49% of 180, round 49% to 50% and 180 to 200. This gives an approximate value of 0.50 × 200 = 100. While this method may not provide the exact answer, it can help you quickly eliminate wrong answer choices in Data Sufficiency questions.

Practice Questions: Mastering GMAT Percentage Tricks

One of the best ways to get comfortable with GMAT percentage tricks is to practice a variety of questions. Regular practice helps you recognize patterns and apply percentage formulas quickly. Below are some sample questions that cover both basic and advanced percentage problems commonly tested on the GMAT.

Basic GMAT Percentage Practice Questions:

Question 1:
A product originally costs $80. It is first discounted by 10%, and then an additional 20% discount is applied to the discounted price. What is the final price of the product?

Solution:
First, apply the 10% discount:

New Price = 80 - (0.10 × 80) = 80 - 8 = 72

Next, apply the 20% discount:

Final Price = 72 - (0.20 × 72) = 72 - 14.4 = 57.6

The final price is $57.60.

Question 2:
If the population of a city increased by 15% over the last year and the current population is 92,000, what was the population a year ago?

Solution:
Let P be the population a year ago. The population increased by 15%, so the equation becomes:

92,000 = P + (0.15 × P)

Simplifying:

92,000 = 1.15 × P  →  P = 92,000 / 1.15 = 80,000

The population a year ago was 80,000.

Advanced GMAT Percentage Practice Questions:

Question 1:
The price of a laptop was increased by 20% and then decreased by 30%. What is the net percentage change?

Solution:
Let’s assume the initial price was $100. After the 20% increase:

New Price = 100 + (0.20 × 100) = 120

After the 30% decrease:

Final Price = 120 - (0.30 × 120) = 120 - 36 = 84

The net percentage change is:

(84 - 100) / 100 × 100 = -16%

So, the price decreased by 16%.

Question 2:
A stock increases by 25% in the first year, then decreases by 10% in the second year, and increases by 15% in the third year. What is the overall percentage change in the stock price after three years?

Solution:
Assume the initial stock price is $100. After a 25% increase:

New Price = 100 + (0.25 × 100) = 125

After a 10% decrease:

New Price = 125 - (0.10 × 125) = 125 - 12.5 = 112.5

After a 15% increase:

Final Price = 112.5 + (0.15 × 112.5) = 112.5 + 16.875 = 129.375

The overall percentage change is:

(129.375 - 100) / 100 × 100 = 29.375%

So, the overall increase is 29.38%.

GMAT Percentage Tricks in Data Sufficiency Questions

Data Sufficiency questions on the GMAT require a unique approach compared to Problem Solving questions. In these questions, the goal is not necessarily to find the answer but to determine whether the given information is sufficient to answer the question. Percentage questions are commonly tested in this format, and mastering them can significantly improve your score.

How to Approach GMAT Percentage Questions in Data Sufficiency:

1. Analyze the Given Information
   In a typical Data Sufficiency question, you will be provided with two statements and asked whether the information is sufficient to answer the question. For example:

   Question: "Is 60% of a number greater than 200?"

   Statement 1: The number is greater than 400.
   Statement 2: The number is less than 300.

   Solution:
   Statement 1: If the number is greater than 400, then 60% × 400 = 240, which is greater than 200. So, Statement 1 is sufficient.
   Statement 2: If the number is less than 300, then 60% × 300 = 180, which is not greater than 200. So, Statement 2 is not sufficient.

   In this example, only the first statement is sufficient to answer the question.

2. Utilize Estimation
   When dealing with percentage-based Data Sufficiency questions, estimation can often save time. For example, if a question asks whether 70% of a number is less than 250, and one of the statements tells you the number is approximately 350, you can quickly estimate that:

     70% × 350 = 245
     

   Since 245 is less than 250, the statement is likely sufficient.

Common Mistakes to Avoid in Data Sufficiency Questions:

1. Not Considering Both Statements Together
   Many students make the mistake of evaluating each statement separately, without considering the possibility that both statements together may provide enough information to solve the problem.
2. Rushing Through the Statements
   When working on percentage questions, it’s important to carefully analyze each statement. Misreading or rushing through the statements can lead to incorrect conclusions.

Real GMAT Example:
Question: "Is 40% of a number less than 100?"
Statement 1: The number is less than 250.
Statement 2: The number is greater than 150.

Solution:
Statement 1: If the number is less than 250, then 40% × 250 = 100, so it’s not possible to determine if 40% is less than 100. Therefore, Statement 1 is not sufficient.
Statement 2: If the number is greater than 150, then 40% × 150 = 60, which is less than 100. Therefore, Statement 2 is sufficient.

Related Blogs

• GMAT divisibility
• Factor and multiple GMAT
• Taking GMAT multiple times
• GMAT fractions
• GMAT integer questions

Conclusion 

Learning GMAT percentage tricks can significantly boost your performance in the quantitative section of the exam. By mastering quick calculation methods, understanding percentage shortcuts, and practicing with real GMAT questions, you can save time and avoid errors on test day. Focus on applying these tricks to common problem types, such as percentage increase or decrease, and comparing percentages, to enhance your accuracy and speed. With consistent practice, these strategies will help you handle percentage questions more confidently and effectively, leading to a better overall GMAT score.