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Ultimate Multiplication Hacks

Topic: Speed Math Updated: All 8 Tricks

Why calculate like a student when you can calculate like a calculator? In competitive exams, the Simplification and Approximation sections test one thing above all else: how fast your brain can multiply. Candidates who rely on traditional long multiplication are at a systematic disadvantage � they might know the same concepts as toppers, but they're solving each question in 45-60 seconds while toppers are done in 15-20.

The 8 multiplication shortcuts below are carefully selected based on IBPS PO, SBI Clerk, and SSC CGL question patterns from 2020-2024. Each trick appears directly in exam questions multiple times every year. Master them, and you'll watch your Quantitative Aptitude marks change dramatically.

1. Magic of 11 � Multiply Any Number by 11 in Seconds

This is the most elegant mental math trick for 2-digit numbers. Works 100% of the time in under 3 seconds.

Rule: "Write the outer digits, insert the sum of digits in the middle"
Example: 24 � 11
1. Write the ends: 2 _ 4
2. Sum: 2+4 = 6 ? insert in middle ? 264 ?
When sum > 9: Example 78 � 11
1. Write ends: 7 _ 8
2. Sum: 7+8 = 15 ? middle digit is 5, carry 1 to 7 ? 858 ?

Exam Application: "Find 63 � 11" is directly tested in Simplification. Also useful in DI calculation chains.

2. Unit Sum = 10, Same Tens Digit � Instant Product!

This unlocks instant multiplication for pairs like 43�47, 61�69, 72�78. Fastest trick for these specific number combinations.

Condition: Same tens digit AND unit digits sum to 10.

Example: 72 � 78 (7 same, 2+8=10)
1. Units: 2 � 8 = 16 (always 2 digits)
2. Tens: 7 � (7+1) = 7 � 8 = 56
?? Answer: 5616 ?
Practice: 43�47, 61�69, 84�86
43�47: 4�5=20, 3�7=21 ? 2021
61�69: 6�7=42, 1�9=09 ? 4209
84�86: 8�9=72, 4�6=24 ? 7224

3. Multiply by 5, 25, 50 � Use Division Instead!

These numbers are halves of powers of 10. Use division to avoid traditional multiplication entirely.

� 5: Halve the number, add a zero
48 � 5: Half of 48 = 24. Add 0 ? 240
73 � 5: Half of 73 = 36.5. Add 0 ? 365
� 25: Divide by 4, add 00
36 � 25: 36�4 = 9. Add 00 ? 900
48 � 25: 48�4 = 12. Add 00 ? 1200
� 50: Halve the number, add 00
48 � 50: Half of 48 = 24. Add 00 ? 2400

Exam Tip: In Approximation questions like "348 � 49.87 � ?", round 49.87 � 50, then use �50 trick: 348 � 50 = 17,400.

4. Base 100 Method � Numbers Near 100

Nikhilam Sutra from Vedic Math. Fastest when both numbers are within �15 of 100.

Example: 96 � 93
1. Deviations from 100: 96?(-4), 93?(-7)
2. Cross subtract: 96-7 = 89
3. Multiply deviations: 4 � 7 = 28
?? Answer: 8928 ?
Example: 107 � 103 (above 100)
Deviations: +7 and +3. Cross add: 107+3 = 110. Product: 7�3=21.
?? Answer: 11021 ?

5. Universal 2-Digit � 2-Digit � The I-X-I (Criss-Cross) Method

Works for ANY two 2-digit numbers. This is the go-to when no special trick applies.

Example: 21 � 32
1. Right (I): 1�2 = 2
2. Cross (X): (2�2)+(1�3) = 4+3 = 7
3. Left (I): 2�3 = 6
?? Read left to right: 672 ?
Example with carry: 37 � 48
Right: 7�8 = 56 ? write 6, carry 5
Cross: (3�8)+(7�4) = 24+28 = 52+5 = 57 ? write 7, carry 5
Left: 3�4 = 12+5 = 17
?? Answer: 1776 ?

6. Multiply by 99, 999 � The Complement Method

Logic: n � 99 = n � (100-1) = 100n - n. Eliminate the special-trick confusion.

Example: 43 � 99
43 � 100 = 4300. Then 4300 - 43 = 4257 ?
Example: 58 � 999
58 � 1000 = 58000. Then 58000 - 58 = 57942 ?

7. Split & Merge � Most Practical General Method

Split the multiplier into convenient parts when no other trick applies.

Example: 24 � 13 = 24 � (10+3)
24 � 10 = 240. 24 � 3 = 72. Total: 240 + 72 = 312 ?
Example: 35 � 17 = 35 � (20-3)
35 � 20 = 700. 35 � 3 = 105. Total: 700 - 105 = 595 ?

8. Double & Half Method � For Decimal Multipliers

Eliminates decimals by doubling one factor and halving the other.

Example: 16 � 3.5
Double 3.5 ? 7. Half 16 ? 8. Then 8 � 7 = 56 ? (No decimals!)
Example: 44 � 7.5
Double 7.5 ? 15. Half 44 ? 22. Then 22 � 15 = 330 ?

Quick Decision Guide: Which Trick for Which Question?

Common Mistakes & How to Avoid Them

FAQ

Q: Which 3 tricks give the most return on investment for IBPS Prelims?
A: Tricks 3 (�5/25/50), 5 (Criss-cross), and 7 (Split & Merge) together cover 90% of Simplification calculations. Master these first, then add the others.

Q: How do I build the reflex to choose the right trick quickly?
A: Deliberate practice with timing. Use Ikkish Prep's Simplification Quiz timed mode. Start slow, consciously apply tricks. After 200+ questions, the right trick selection becomes automatic � faster than your conscious mind can "decide."

Practice makes perfect! Start your Simplification Quiz on Ikkish Prep now and apply one new trick per day until all 8 are instinctive reflexes.

Practice makes perfect!

Start Practice