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Master Mental Math for Quant Interviews

Build lightning-fast arithmetic skills with our Zetamac-style trainer. Used by candidates who landed offers at Jane Street, Citadel, and Optiver.

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What is Zetamac?

Zetamac revolutionized mental math training by introducing a simple yet effective format: solve as many arithmetic problems as possible in 2 minutes. What started as a tool for competitive mathematics has become the de facto standard for quant interview preparation.

The brilliance lies in its simplicity. No complex UI, no gamification gimmicks—just you against the clock. This laser focus on speed and accuracy mirrors exactly what you'll face in real quant interviews, where mental math determines whether you advance to the next round.

2
Minutes per test
40+
Target score
6
Seconds per problem

Why Speed Matters in Quant Finance

The Optiver 80-in-8 Test

Optiver's legendary assessment gives you 8 minutes to solve 80 problems. That's 6 seconds per question—no time to second-guess. Your mental math speed directly determines whether you get a trading interview.

Jane Street Live Trading

During Jane Street interviews, you'll calculate expected values while explaining your reasoning. Slow arithmetic means fumbling through basic math instead of showcasing your problem-solving skills.

Real-Time Market Making

Market makers update prices hundreds of times per second. When volatility spikes, you need instant calculations for position sizing, hedge ratios, and P&L. There's no Excel in the heat of trading.

“The difference between a good trader and a great one often comes down to who can process information faster. Mental math is the foundation.”— Former Optiver Trader

Speed Calculation Techniques

×Multiplication Shortcuts

Squares Near Round Numbers

48² = (50-2)² = 2500 - 200 + 4 = 2304

Use the formula: (n±a)² = n² ± 2na + a²

Numbers Ending in 5

65² = 6×7 = 42, then append 25 → 4225

Multiply the tens digit by (tens digit + 1), append 25

Cross Multiplication

97×103 = (100-3)(100+3) = 10000 - 9 = 9991

Use difference of squares: (a-b)(a+b) = a² - b²

÷Division Patterns

Divisibility Tests

÷3Sum of digits divisible by 3
÷9Sum of digits divisible by 9
÷11Alternating sum = 0
÷4Last 2 digits divisible by 4

Fraction Conversions

1/8 = 0.125
3/8 = 0.375
5/8 = 0.625
1/9 = 0.111...
1/6 = 0.167
1/7 = 0.143

Performance Benchmarks

15-25

Needs Work

Focus on fundamentals

26-35

Good Progress

Building speed

36-45

Interview Ready

Competitive level

46+

Elite

Top 5% speed

Industry Standards

  • •Optiver: Minimum 56/80 to pass (70% accuracy)
  • •Jane Street: Expects 35+ problems in 2 minutes
  • •IMC Trading: Tests speed under time pressure

30-Day Training Plan

W1

Foundation Building

Master the basics without time pressure. Focus on accuracy.

  • 10 min/day multiplication tables
  • 15 min/day untimed practice
  • Learn one new shortcut daily
W2

Speed Introduction

Add time pressure. Track daily progress.

  • 2-minute timed sessions
  • Target: 20+ problems
  • Focus on multiplication shortcuts
W3-4

Interview Preparation

Simulate real interview conditions. Push for consistency.

  • Consistent 35+ problems
  • 3 sessions daily
  • Practice explaining solutions aloud

Ready to Build Elite Speed?

Join thousands of candidates who improved their mental math from average to elite. Start with a 2-minute test and see where you stand.

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