100 Quant Shortcuts for IBPS RRB Clerk Exam with Examples

In the IBPS RRB Clerk Quant/ Numerical Ability section, speed and accuracy are everything. With only 20 minutes to solve 40 questions, you can’t afford long calculations. That’s where shortcuts come in. Using them reduces time to calculate the answer to a question. When you learn and apply them in mock tests, your speed improves. Below, you’ll find 100 powerful tricks across all arithmetic topics, each explained with an example so you can apply them in your tests and score well in the exam.

Topic-wise 100 Quant Arithmetic Shortcuts for RRB Clerk Exam

Mastering topic‑wise 100 Quant Arithmetic shortcuts for the IBPS RRB Clerk exam is all about breaking down each chapter into its most efficient formulas and time‑saving tricks. From percentages, profit and loss, averages, and ages to more complex areas like simple and compound interest, mixture and alligation, time–speed–distance, time and work, and data interpretation, every topic has its own set of quick methods that cut calculation time drastically. For example, using the alligation rule in mixtures, successive percentage formulas for profit and loss, or LCM methods in time and work can help solve questions in seconds instead of minutes. Check topic-wise quant shortcuts with an example given below.

Percentages (10 Shortcuts)

1. x% of y = y% of x
   Example: 25% of 200 = 200×25/100 = 50. Or 200% of 25 = 50.
   
2. Increase by x% then decrease by x% → Net change = –(x²/100)
   Example: Increase 100 by 20% → 120. Then decrease by 20% → 96. Net change = –4%. Formula: –(20²/100) = –4%.
   
3. Fraction to % conversions
   Example: 1/8 = 12.5%, 3/20 = 15%. Memorize common ones for speed.
   
4. Successive % change formula: A + B + (AB/100)
   Example: Increase 20% then 10% → Net = 20+10+(20×10/100) = 32%.
   
5. % change = (Difference/Base)×100
   Example: From 80 to 100 → (20/80)×100 = 25%.
   
6. If A is x% more than B → B is (x/(100+x))% less than A
   Example: A is 25% more than B → B is 25/125 = 20% less than A.
   
7. If A is x% less than B → B is (x/(100–x))% more than A
   Example: A is 20% less than B → B is 20/80 = 25% more than A.
   
8. Quick % mental math
   Example: 10% = ÷10, 5% = ÷20, 1% = ÷100. So 5% of 240 = 240÷20 = 12.
   Learn 1 to 100 percent to fraction conversion from here.
9. Cancel zeros before multiplying
   Example: 25% of 2400 = (25×24) = 600.
   
10. Approximation for DI
    Example: 19.8% of 499 ≈ 20% of 500 = 100.

Profit & Loss (8 Shortcuts)

11. Profit% = (Profit/CP)×100
    Example: CP=100, SP=120 → Profit=20 → Profit%=20%.
    
12. SP = CP × (100+Profit%)/100
    Example: CP=500, Profit%=20 → SP=500×120/100=600.
    
13. CP = SP × 100/(100+Profit%)
    Example: SP=600, Profit%=20 → CP=600×100/120=500.
    
14. Successive profit/loss
    Example: 20% profit then 10% loss → Net=20–10+(20×–10/100)=8% profit.
    
15. Discount% = (MRP–SP)/MRP×100
    Example: MRP=1000, SP=800 → Discount=20%.
    
16. Two successive discounts
    Example: 20% then 10% → Net=20+10–(20×10/100)=28%.
    
17. Marked Price = SP×100/(100–Discount%)
    Example: SP=800, Discount=20% → MP=800×100/80=1000.
    
18. Chain transactions
    Example: CP=100, Profit=20% → SP=120. Then sold at 10% loss → Final SP=108.

Partnership (5 Shortcuts)

19. Profit share ∝ Investment×Time
    Example: A invests 6000 for 12 months, B invests 9000 for 8 months → Ratio=72000:72000=1:1.
    
20. Adjust for time
    Example: A invests 5000 for 12 months, B invests 5000 for 6 months → Ratio=5000×12:5000×6=2:1.
    
21. Sleeping partner
    Example: If C invests nothing, his share=0.
    
22. Back‑calculate investments
    Example: Profit ratio=2:3, Time same → Investment ratio=2:3.
    
23. Multiple partners
    Example: A=6000×12, B=9000×8, C=12000×6 → Ratio=72000:72000:72000=1:1:1.

You can also look at the quant formulas and concepts well explained here!

Ages (5 Shortcuts)

24. Use algebra
    Example: Father=4x, Son=x. After 5 years: (4x+5)/(x+5)=3 → Solve.
    
25. After n years = x+n
    Example: Son=10, after 5 years=15.
    
26. Difference constant
    Example: Father=40, Son=10 → Difference=30 always.
    
27. Average age
    Example: 5 persons, avg=20 → Total=100.
    
28. Replacement
    Example: Avg=20, one leaves (25), new avg=19 → New person=14.

Averages (6 Shortcuts)

29. Average=Sum/Number
    Example: (10+20+30)/3=20.
    
30. New average
    Example: Old avg=20, 5 numbers=100. Add 30 → New avg=(130/6)=21.67.
    
31. Weighted average
    Example: 2 students avg=20, 3 students avg=30 → Weighted avg=(2×20+3×30)/5=26.
    
32. Replacement formula
    Example: Old avg=20, replaced 25 with 30 → New avg=20+(30–25)/n.
    
33. Consecutive numbers
    Example: 1 to 9 → Avg=5.
    
34. Even consecutive
    Example: 2,4,6,8 → Avg=(2+8)/2=5.

Simple & Compound Interest (10 Shortcuts)

35. SI=(P×R×T)/100
    Example: 1000 at 10% for 2 yrs=200.
    
36. Amount=P+SI
    Example: 1000+200=1200.
    
37. CI=P[(1+R/100)^T–1]
    Example: 1000 at 10% for 2 yrs=1000×(1.21–1)=210.
    
38. Difference CI–SI (2 yrs)=P×(R²/100²)
    Example: 1000 at 10% → 1000×0.01=10.
    
39. For 3 yrs
    Example: Formula extension.
    
40. Half‑yearly CI
    Example: 1000 at 10% for 1 yr → R=5%, T=2 → CI=1000×(1.05²–1)=102.5.
    
41. Quarterly CI
    Example: 1000 at 12% for 1 yr → R=3%, T=4 → CI=1000×(1.03⁴–1)=125.5.
    
42. Rule of 72
    Example: At 12% → Double in 72/12=6 yrs.
    
43. Rule of 69
    Example: At 10% → Double in 69/10≈7 yrs.
    
44. Recurring deposits
    Example: Use AP formula.

Mixture & Allegation (5 Shortcuts)

45. Mean Price Formula
Mean Price = (Qty₁×Price₁ + Qty₂×Price₂)/(Qty₁+Qty₂)
Example: 2 kg rice at ₹50/kg and 3 kg at ₹60/kg → Mean = (100+180)/5 = ₹56/kg.

46. Rule of Allegation (Shortcut Ratio)
Ratio = (High–Mean):(Mean–Low)
Example: Mix milk at ₹6/litre and water at ₹2/litre to sell at ₹4/litre → Ratio = (6–4):(4–2) = 2:2 = 1:1.

47. Milk–Water Problems
Example: If 1 litre water is added to 4 litres milk, ratio = 4:1.

48. Replacement Formula
Final concentration = Initial × (1–x/n)^k
Example: 100 litres milk, 10 litres replaced with water, repeated twice → Final milk = 100×(1–10/100)² = 81 litres.

49. Successive Mixtures
Apply allegation step by step for each mixing.

50. Shortcut Tip
Always subtract diagonally in allegation to avoid confusion.

Ratio & Proportion (5 Shortcuts)

51. Chain Ratios
If a:b and b:c → a:b:c.
Example: a:b=2:3, b:c=4:5 → a:b:c=8:12:15.

52. Inverse Ratio
If work is inversely proportional to time.
Example: A:B=2:3 in efficiency → Time ratio=3:2.

53. Direct Proportion
a₁/b₁=a₂/b₂.
Example: 2 pens cost ₹10, 5 pens cost x → x=25.

54. Compound Ratio
Multiply ratios term‑wise.
Example: (2:3)×(4:5)=8:15.

55. Distribution
Total × (Ratio part/Total ratio).
Example: ₹600 divided in 2:3 → A=600×2/5=240, B=360.

Time, Speed & Distance (10 Shortcuts)

56. Speed=Distance/Time
120 km in 2 hrs → 60 km/h.

57. Time=Distance/Speed
120 km at 60 km/h → 2 hrs.

58. Distance=Speed×Time
60 km/h × 2 hrs=120 km.

59. Time ∝ 1/Speed
If speed doubles, time halves.

60. Relative Speed (Opposite)
u+v.
Example: 60 & 40 km/h opposite → 100 km/h.

61. Relative Speed (Same)
u–v.
Example: 60 & 40 km/h same → 20 km/h.

62. Average Speed Formula
2xy/(x+y).
Example: 60 km/h one way, 40 km/h return → Avg=48 km/h.

63. Distance Same → Speed Ratio = Inverse Time Ratio
Example: Time ratio 2:3 → Speed ratio 3:2.

64. Time Same → Distance Ratio = Speed Ratio
Example: Speed ratio 2:3 → Distance ratio 2:3.

65. Train Crossing
Time=Length/Speed.
Example: Train 120m, speed 60 km/h=16.67 m/s → Time=120/16.67≈7.2s.

Time & Work (8 Shortcuts)

66. Work=Time×Efficiency

67. Efficiency=1/Days
A completes in 10 days → Efficiency=1/10.

68. Combined Work=Sum of Efficiencies
A=1/10, B=1/20 → Together=3/20 → 20/3 days.

69. Efficiency Ratio → Time Ratio
If A:B efficiency=2:3 → Time ratio=3:2.

70. LCM Method
Take total work=LCM of days.
Example: A=10 days, B=20 days → LCM=20 units.

71. Alternate Days
Calculate 2‑day cycle.
Example: A=1/2, B=1/3 → 2‑day work=5/6.

72. Pipes & Cisterns
Inlet=+ve, Outlet=–ve.

73. Net Work=Sum of Rates
A=1/6, B=1/4, C=–1/12 → Net=1/6+1/4–1/12=1/3.

Boats & Streams (4 Shortcuts)

74. Downstream=u+v
Boat=10, Stream=2 → 12.

75. Upstream=u–v
Boat=10, Stream=2 → 8.

76. Time=Distance/Speed

77. Boat Speed Formula
d downstream in t₁, upstream in t₂ → Boat speed=d(1/t₁+1/t₂)/2.

78. Stream Speed Formula
d downstream in t₁, upstream in t₂ → Stream speed=d(1/t₁–1/t₂)/2.

DI Shortcuts (10 Shortcuts)

79. Approximate values

• Don’t waste time on exact decimals. Round numbers sensibly (e.g., 49.8 ≈ 50) to speed up calculations, especially when options are far apart. Round off for speed. You should check if the options are too close.

80. Use % multipliers

• Convert percentage changes into multipliers.
  Example: 20% increase = ×1.2; 10% decrease = ×0.9.
  This avoids repeated percentage calculations.

81. Pie chart

• Remember: 360° = 100%.
  So, 1° = (Total ÷ 360). Quickly convert angles into values or percentages.

82. Bar graph

• Focus on ratios and relative heights, not just absolute values. Ratios often give faster answers than calculating exact numbers.

83. Line graph

• The slope (upward/downward) shows the trend. Steeper slope = faster change. Use this to answer “increase/decrease” type questions quickly.

84. Table DI

• Use the difference method: Instead of calculating totals repeatedly, subtract or compare directly between rows/columns to save time.

85. Round decimals smartly

• For decimals like 19.98, treat as 20 if options allow. But be careful when options are close—then calculate precisely.

86. 1% = Total ÷ 100

• A universal trick: To find any percentage, first find 1% of the total, then multiply.
  Example: 17% of 2400 → 1% = 24 → 17% = 24 × 17 = 408.

87. Growth rate

• Use the successive % formula:
  If increase by x% and then y%, net % = x + y + (xy/100).
  Saves time over stepwise calculation.

88. Average in DI

• Average = Total sum ÷ Number of items.
  In DI, add all required values first, then divide; don’t average step by step.

89. Ratio DI

• Always simplify ratios before multiplying. Smaller numbers = faster calculations.
  Example: 120:180 → 2:3.

90. Missing DI

• When data is incomplete, form equations directly from given conditions. Solve algebraically instead of guessing.

Miscellaneous Arithmetic (10 Shortcuts)

91. HCF×LCM=Product of numbers
Example: 12 & 18 → HCF=6, LCM=36 → Product=216.

92. Divisibility Rules
2 (last digit even), 3 (sum divisible by 3), 5 (last digit 0/5), 7 (double last digit subtract), 11 (alt sum diff divisible by 11).

93. Memorize Squares & Cubes
Squares up to 30, cubes up to 20.

94. (a+b)²=a²+b²+2ab
Example: 12²=(10+2)²=100+4+40=144.

95. (a–b)²=a²+b²–2ab
Example: 98²=(100–2)²=10000+4–400=9604.

96. (a+b)(a–b)=a²–b²
Example: 102×98=(100+2)(100–2)=10000–4=9996.

97. (x+y+z)²=x²+y²+z²+2(xy+yz+zx)

98. Remainder Problems
Use modular arithmetic.
Example: 7 divides 1001 → Remainder=0.

99. Simplification
Use BODMAS and approximation.

100. Reciprocals
Memorize 1/2=0.5, 1/3=0.333, 1/4=0.25 … up to 1/20.

How to Remember These Shortcuts?

The best way to retain all 100 quant shortcuts is not by rote memorization but by understanding the logic behind each one. Every shortcut is derived from a basic mathematical principle; if you don’t know how it’s made, mugging it up will only confuse you in the exam hall. Start by practicing each shortcut on simple examples to see why it works. Once the logic is clear, apply it in topic‑wise quizzes (e.g., percentages, averages, ratios) to strengthen recall. Next, move to sectional mocks, where you’ll face mixed DI and arithmetic sets. This helps you decide quickly which shortcut to apply under time pressure. Finally, use full‑length mock tests to simulate exam conditions and train your brain to recall shortcuts naturally. Over time, the repeated cycle of learn → apply → test → revise will make these shortcuts on your fingertips, so you can solve faster without second‑guessing.

Conclusion

These 100 shortcuts with examples are your toolkit for cracking the Quant section in IBPS RRB Clerk. The more you practice them in mocks and previous year papers, the faster you will become habitual to them. Remember: shortcuts save time, but accuracy comes from practice.

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