5 Mental Maths Tricks to Improve Calculation Speed for Competitive Exams
Discover 5 powerful mental maths tricks to calculate faster without a calculator. Improve calculation speed for Olympiads, NTSE, JEE Foundation, and competitive exams.
6/30/20263 min read
Whether you're preparing for school exams, Olympiads, JEE Foundation, NTSE, or other competitive exams, calculation speed can make a significant difference. Students often know the correct method but lose valuable marks because they spend too much time on calculations.
The good news is that you don't always need lengthy calculations. By learning a few simple mental maths tricks, you can solve many problems much faster while improving your confidence.
Let's explore five practical techniques that every student from Grade 6 to Grade 10 should know.
1. Multiply Any Two-Digit Number by 11
This is one of the easiest and most useful mental maths tricks.
Example 1
43 × 11
Step 1: Write the first digit.
4 _ 3
Step 2: Add the two digits.
4 + 3 = 7
Step 3: Place the sum in the middle.
Answer: 473
Example 2 (Carry Case)
87 × 11
8 + 7 = 15
Write 5 in the middle and carry 1.
Final answer: 957
2. Square Numbers Ending in 5
Squaring numbers ending in 5 becomes incredibly simple with this trick.
Rule
Suppose the number is n5.
Multiply n × (n + 1).
Write 25 at the end.
Example 1
35²
3 × 4 = 12
Answer: 1225
3. Multiply Numbers Close to 100
This trick works beautifully when both numbers are close to 100.
Example
98 × 97
Step 1
98 is 2 less than 100.
97 is 3 less than 100.
Step 2
98 − 3 = 95
(or 97 − 2 = 95)
Step 3
Multiply the differences.
2 × 3 = 6
Since the base is 100, write it as 06.
Final answer: 9506
Example Above 100
103 × 106
103 + 6 = 109
3 × 6 = 18
Answer: 10918
What if one is above 100 and other below 100? Find out here.
4. Square Any 2-Digit Number in Seconds (Duplex Method)
Most students know shortcuts only for numbers ending in 5. But what if you could quickly square any two-digit number mentally?
The Duplex Method from Vedic Mathematics provides a systematic way to do this.
The Formula
For a two-digit number AB,
(AB)^2 = A^2 | 2×A×B | B^2
Then work from right to left, carrying over whenever a part exceeds 9.
Example 1: Find 67²
Here,
A = 6
B = 7
Step 1: Calculate the three parts
A² = 6² = 36
2 × A × B = 2 × 6 × 7 = 84
B² = 7² = 49
So we get:
36 | 84 | 49
Step 2: Process from right to left
49 → Write 9, Carry 4
84 + 4 = 88 → Write 8, Carry 8
36 + 8 = 44
Answer = 4489
5. Calculate Percentages Mentally
Many students find percentage questions time-consuming.
Instead of memorising formulas, remember these simple facts.
10% = Divide by 10
5% = Half of 10%
25% = Divide by 4
50% = Divide by 2
12.5% = Divide by 8
Example 1
15% of 480
10% = 48
5% = 24
48 + 24 = 72
Example 2
25% of 320
320 ÷ 4 = 80
Example 3
12.5% of 400
400 ÷ 8 = 50
Tips to Improve Calculation Speed
Learning tricks alone won't make you fast. Here are a few habits followed by top-performing students:
Practice mental calculations every day for 10–15 minutes. (Try HazyMaths competitive - Link)
Estimate the answer before solving.
Avoid using a calculator for simple calculations.
Learn multiplication tables up to 25.
Revise fractions, percentages, and squares regularly.
Solve timed practice questions to build speed under pressure.
Consistent practice is the key to becoming faster and more accurate.
Final Thoughts
Mental maths tricks can save valuable time in examinations, but they should support your understanding—not replace it. Strong concepts, regular practice, and smart calculation techniques together build mathematical confidence.
Whether you're preparing for school exams, Olympiads, JEE Foundation, or other competitive exams, improving your calculation speed will help you solve more questions accurately within the available time.
If you want to develop strong mathematical concepts along with calculation speed, logical reasoning, and problem-solving skills, explore the MasterLeap Tutor Mathematics Master Foundation Series (Grades 6–10). The series is carefully designed to help students progress from school-level mathematics to Olympiad and JEE Foundation preparation through clear explanations, challenging exercises, and step-by-step learning.
Frequently Asked Questions (FAQs)
Is mental maths useful for competitive exams?
Yes. Faster calculations save valuable time, allowing you to spend more time on difficult questions. Mental maths is especially useful for Olympiads, JEE Foundation, NTSE, and aptitude tests.
Can students from Grade 6 learn these tricks?
Absolutely. These tricks are simple enough for students from Grade 6 onwards and become more useful as mathematical difficulty increases.
Is mental maths the same as Vedic Maths?
Not exactly. Mental maths refers to performing calculations in your head using different strategies. Vedic Maths is one system that offers many useful mental calculation techniques.
How can I improve my calculation speed?
Practice regularly, learn multiplication tables thoroughly, solve questions without a calculator, revise percentages and squares, and use mental maths shortcuts whenever appropriate.
Do these tricks replace understanding mathematical concepts?
No. These techniques help speed up calculations, but conceptual understanding remains the foundation of success in mathematics.