Quick Calculation Techniques for School Students

Turn math into a fun challenge for students! Check out 17 quick calculation techniques that parents and educators can use to help improve calculation speed and accuracy.

Jasdeep Singh25 Apr, 2025

Math can feel slow and frustrating when calculations take too long, especially during exams or everyday situations like shopping or splitting bills. But what if you could solve problems in seconds using simple tricks?

In this blog post, we will discuss 17 Math tricks that can help you:

Add and subtract numbers quickly
Multiply large numbers with ease
Find percentages without complicated steps
Improve accuracy while saving time

By using these methods, you can handle calculations faster and more efficiently in both academic and real-life situations.

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17 Must-Know Math Tricks for Fast Calculations

Why spend extra time on math when you can solve it in seconds? These 18 shortcuts will help you multiply, divide, and calculate with speed and accuracy.

1. The Rounding Method for Quick Addition

Adding large numbers can sometimes be tricky, especially when dealing with odd values. Instead of adding directly, a smart approach is to round up the numbers to the nearest multiple of 10, perform the addition, and then adjust accordingly.

For example, let’s add 48 + 77. Instead of adding them directly:

Round 48 to 50 and 77 to 80.
Add these rounded numbers: 50 + 80 = 130.
Since we added 2 to 48 and 3 to 77, we subtract their sum from 130:

130 - (2 + 3) = 125.

This trick simplifies addition and reduces errors when dealing with large numbers.

2. Borrowing Trick for Faster Subtraction

Subtraction often requires borrowing, which can be time-consuming. A quick way to subtract is by adjusting the number to make calculations easier.

Let’s consider 1900 - 1847.

Instead of subtracting directly, round up 1847 to 1850.
Now subtract: 1900 - 1850 = 50.
Since we increased 1847 by 3, we add it back: 50 + 3 = 53.

This technique avoids unnecessary borrowing, making subtraction faster and easier.

3. Multiplying Any Number by 5 Instantly

Multiplying by 5 can be done in a fraction of the time by following this method:

If the number is even, divide it by 2 and add a zero at the end.

Example: 48 × 548

Step 1: 48/2 = 24

Step 2: Add a zero → 240

If the number is odd, subtract 1, then divide by 2, and add 5 at the end.

Example: 27 × 527

Step 1: 27−1 = 26

Step 2: 26/2 = 13

Step 3: Add 5 → 135

This method saves time and eliminates complex multiplication steps.

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4. Multiplying Any Two-Digit Number by 11

Multiplying by 11 is made easy with this trick. To multiply a two-digit number by 11, follow these steps:

Separate the two digits.
Find their sum and place it between them.

Example: 61×11

Split: 6_1
Sum of digits: 6 + 1 = 7
Insert in between: 671

Another example: 45 × 11

Split: 4_5
Sum: 4 + 5 = 9
Insert: 495

If the sum is greater than 9, carry over the extra digit.

5. The Criss-Cross Method for Multiplication

This method simplifies two-digit multiplication by breaking it into smaller steps.

Example: 43 × 12

Multiply the ones place: 3 × 2 = 6

Cross-multiply and add: (4 × 2) + (3 × 1) = 8 + 3 = 11

Multiply the tens place and add carry: 4 × 1 + 1(carry) = 5

54 × 1 +1(carry) = 5.

Final result: 516

This method reduces complex multiplication into easy mental steps.

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6. Divide Large Numbers by 5 in Seconds

Dividing a large number by 5 is simpler than it seems.

Example: 3456/5

Multiply by 2: 3456 × 2 = 6912
Move the decimal one place left: 691.2

Final answer: 691.2

This trick works faster than traditional long division.

7. Squaring Numbers Ending in 5 Instantly

For numbers ending in 5, squaring them is simple:

Multiply the first digit by its next consecutive number.
Add 25 at the end.

Example: 352

3 × 4 = 12 times
Append 25 → 1225

Example: 752

7 × 8 = 56
Add 25 → 5625

This trick eliminates lengthy multiplication steps.

8. Finding Cube Roots of Perfect Cubes

Cube roots of perfect cubes follow a pattern based on their unit digits.

Example: Cube root of 117649

Step 1: Identify the last digit: 9, so the unit place of the cube root is 9.

Step 2: Look at the first part 117, and check the nearest perfect cubes.

Step 3: Since 4³ = 64 and 5³ = 125, the first digit is 4.

Final answer: 49.

9. Multiplication by 15 Using a Shortcut

To multiply by 15, use this method:

Step 1: Multiply by 10.

Step 2: Find half of that product.

Step 3: Add both values together.

Example: 56 × 15

56 × 10 = 560
560/2 = 280
560 + 280=840

This method avoids direct multiplication, making it easier.

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10. Finding Percentages Easily

For quick 5% calculations, simply divide the number by 2 after moving the decimal one place left.

Example: 5% of 475

Move decimal: 47.5
Divide by 2: 23.75

Final answer: 23.75.

11. Checking Divisibility Rules Quickly

A number is divisible by 2 if it ends in 0, 2, 4, 6, or 8.
A number is divisible by 3 if the sum of its digits is a multiple of 3.
A number is divisible by 9 if the sum of its digits is a multiple of 9.

12. Memorizing the Table of 9 Using a Pattern

Notice this pattern in the 9’s table:
09, 18, 27, 36, 45, 54, 63, 72, 81, 90

The tens place increases by 1.
The ones place decreases by 1.

13. Multiplying by 99 in Seconds

Instead of multiplying directly by 99, use this trick:

Example: 47 × 99

Multiply by 100: 47 × 100 = 4700
Subtract the number: 4700 − 47 = 4653

14. Shortcut to Find the Square Root

When you need to find the square root of a number, check the last digit of the number. If the last digit is 9, the square root will end in either 3 or 7. This shortcut helps narrow down the possibilities.

Example:

Let’s take the number 7569.

The last digit is 9, so we know the square root of 7569 will end in either 3 or 7.

Now, let’s check both possibilities:

Check if it ends in 3:
73 × 73 = 5329 (This is not 7569, so the square root doesn’t end in 3).

Check if it ends in 7:
87 × 87 = 7569 (This is correct!)

So, the square root of 7569 is 87.

15. The Halving and Doubling Method for Multiplication

For even numbers, halve one number and double the other.

Example: 18 × 37

18/2 = 9, 37 × 2 = 74
Multiply: 9 × 74 = 666

16. Close Together Multiplication

For numbers like 34 × 36, use:

(n + a)(n + b) = n(n + a + b) +ab

30(40) + 24 = 1224

17. Converting Decimals to Percentages Instantly

To convert a decimal to a percentage, simply move the decimal point two places to the right and add a % sign. This works because multiplying by 100 turns a decimal into a percentage.

Examples:

1.6 → 160%
0.75 → 75%
0.03 → 3%
12.4 → 1240%

This trick makes percentage calculations quick and easy, especially in exams and real-life applications like discounts or interest rates.

Math doesn't have to be a struggle for children. These quick calculation techniques help young learners develop speed and confidence in solving problems. With regular practice, any child can master these tricks and start calculating like a pro!

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