Top 7 Mental Math Strategies for Competitive Exams

Preparing for competitive exams like CAT, SSC, Banking, or GRE? Then you already know that time is your biggest enemy in the quant section. While knowing formulas and practicing questions is important, mental math is the secret weapon that can truly help you stay ahead.

In this post, we’re breaking down 7 powerful mental math strategies that you can start using today to speed up your calculations, reduce silly mistakes, and improve your overall accuracy and confidence.

1. Break and Simplify (Using Number Splits)

Instead of multiplying or adding big numbers directly, break them down into manageable parts.

Example:
Calculate 43 × 6
Break it as: (40 × 6) + (3 × 6) = 240 + 18 = 258

This strategy reduces the mental load and prevents mistakes, especially during multiplications.

2. Use Base Method for Multiplication

When multiplying numbers close to a round figure (like 100, 1000), use the base method.

Example:
97 × 96
Both are close to 100.
97 is -3 from 100, and 96 is -4 from 100.
So:
Left Part: 97 - 4 = 93
Right Part: 3 × 4 = 12
Answer = 9312

This is especially useful in questions involving numbers around common bases.

3. Multiply Using Vedic Math Tricks

One of the best-known Vedic tricks is for squaring numbers ending in 5.

Example:
Find 75²
Step 1: Take the first digit (7)
Step 2: Multiply it with its next number (7 × 8 = 56)
Step 3: Add 25 to the end
Final Answer: 5625

This shortcut works like a charm for numbers ending in 5 and helps avoid full multiplication.

4. Use Approximation Smartly

In competitive exams, options are often far apart, so exact answers aren’t always necessary.

Example:
12.93 × 4.98
Round it off: 13 × 5 = 65
Quick, good enough, and saves time — unless options are very close.

Train your brain to spot when approximation is safe and when accuracy is essential.

5. Cross Multiplication for Fractions

Comparing fractions? No need to find LCM or convert them.

Example:
Which is bigger: 5/7 or 3/4?
Cross multiply:
5 × 4 = 20
3 × 7 = 21
Since 21 > 20 → 3/4 is greater

This trick works instantly and avoids tedious calculations.

6. Use the Rule of 11 for Multiplication

A fun and quick trick for two-digit numbers multiplied by 11.

Example:
52 × 11
Add 5 + 2 = 7
Place it between: 572

For 11 × 43 → 4 + 3 = 7 → 473
If the middle number is two-digit, carry over accordingly.

7. Learn Square and Cube Values Till 30

It’s a no-brainer but often ignored. Memorize squares and cubes up to 30. It pays off in simplification, data interpretation, and algebra questions.

Example:
If you instantly know that 27² = 729 or 17³ = 4913, you can cut calculation time in half.

Create a daily flashcard routine and revise these values regularly.

Final Thoughts

Mental math isn’t just about speed — it's about smart calculation and clarity of thought. Once you start practicing these techniques, you'll notice how your accuracy improves, your confidence grows, and your problem-solving time drops significantly.

Remember, competitive exams don’t just test your knowledge — they test how efficiently you can apply it under pressure. And that’s where these mental math strategies give you the edge.

Start small, practice daily, and soon, these tricks will become second nature.

Stay sharp and keep solving!