Mental Math for Quant Interviews

Master speed math tricks and mental calculation techniques used by professional traders. Practice with timed exercises designed specifically for quantitative trading interviews.

Speed Math Tricks

Learn proven mental math techniques used by professional traders to calculate quickly and accurately under pressure.

Timed Practice

Practice with realistic time constraints that mirror actual quant interview conditions and trading floor scenarios.

Interview-Focused

Exercises specifically designed for quant interviews at top firms like Flow Traders, Jane Street, and Citadel.

Essential Mental Math Tricks for Quant Interviews

Trick 1: Break Down Large Numbers

247 + 156 = ?

Step 1: Break into hundreds and tens: (200 + 100) + (47 + 56)

Step 2: Calculate: 300 + 103 = 403

Result: 247 + 156 = 403

Trick 2: Fraction Addition

3/4 + 1/6 = ?

Step 1: Find common denominator: 12

Step 2: Convert: 9/12 + 2/12 = 11/12

Result: 3/4 + 1/6 = 11/12

Trick 3: Percentage Calculations

15% of 240 = ?

Step 1: 10% of 240 = 24

Step 2: 5% of 240 = 12

Result: 15% of 240 = 36

Trick 4: Square Numbers

23² = ?

Step 1: Use formula: (a + b)² = a² + 2ab + b²

Step 2: 20² + 2(20)(3) + 3² = 400 + 120 + 9

Result: 23² = 529

Practice Exercises by Difficulty

Beginner Level
Basic arithmetic and simple calculations
  • • Addition and subtraction (2-3 digits)
  • • Basic multiplication tables
  • • Simple percentage calculations
  • • Basic fraction operations
Intermediate Level
Complex calculations and time pressure
  • • Multi-digit multiplication
  • • Complex fraction operations
  • • Percentage and ratio problems
  • • Square and square root calculations
Advanced Level
Expert-level calculations under pressure
  • • Complex multi-step calculations
  • • Advanced percentage problems
  • • Compound interest calculations
  • • Statistical calculations

Firm-Specific Mental Math Practice

Flow Traders Test
75 questions in 8 minutes
  • • Basic arithmetic
  • • Fractions and decimals
  • • Missing number problems
  • • +1/-2 scoring system
Jane Street Math
Quantitative reasoning focus
  • • Probability calculations
  • • Market making problems
  • • Complex arithmetic
  • • Real-time calculations
Optiver 80in8
80 questions in 8 minutes
  • • Speed arithmetic
  • • Pattern recognition
  • • Sequence problems
  • • High-pressure timing

Frequently Asked Questions

How fast should I be able to calculate for quant interviews?

Most quant interviews expect you to solve basic arithmetic problems in 5-10 seconds. For complex calculations, you should aim for 15-30 seconds. The key is accuracy under pressure, not just speed.

What mental math tricks are most important for trading interviews?

Focus on: percentage calculations, fraction operations, square numbers, and breaking down large numbers. These are the most commonly tested skills in quantitative trading interviews.

How can I improve my mental math speed?

Practice daily with timed exercises, memorize common calculations, use visualization techniques, and practice under pressure to simulate interview conditions.

Ready to Master Mental Math?
Start practicing with our comprehensive mental math training program designed specifically for quant interviews.