I recently completed the Online Assessment for Optiver Software Engineer / Trading roles. Unlike typical tech OAs, this one feels more like a full-spectrum evaluation — combining mental math, logic, probability, reaction speed, and coding into a single pipeline.
Based on both recent (2025–2026) candidate experiences and my own attempt, here is a structured breakdown of the OA format, high-frequency question types, and preparation strategies.
OA Structure (2026 Updated)
The assessment typically lasts 2.5 to 3 hours and consists of five sections:
- 80 in 8 (Mental Math) — 80 questions in 8 minutes
- NumberLogic / Sequences — pattern recognition
- Beat the Odds — probability & decision-making
- Zap-N — cognitive reaction games
- Coding (HackerRank) — 2–3 algorithm problems
Key insight: The first four sections are the real filters. Many candidates do not even make it to the coding stage.
High-Frequency Question Types
80 in 8 (Mental Math)
This is the most critical and challenging section. The difficulty lies not in complexity, but in extreme time pressure.
Common Topics
- 3-digit × 2-digit multiplication
- Division and approximations
- Percentages (e.g., 17% of 350)
- Fraction operations
Preparation Tips
- Train mental calculation speed, not written methods
- Accuracy matters more than attempting all questions
- A solid target: 60+ attempted with 70%+ accuracy
NumberLogic (Sequences)
This section resembles IQ-style pattern recognition but can vary significantly in difficulty.
Common Patterns
- Increasing differences
- Squares / cubes
- Fibonacci variations
- Prime number patterns
Example
2, 3, 5, 8, 12, 17, ? → Answer: 23
Preparation Tips
- Check differences first
- Then consider multiplicative or hybrid patterns
- Focus on recognition speed over deep reasoning
Beat the Odds (Probability & Game Theory)
This section strongly reflects quantitative thinking ability and often differentiates candidates.
Common Topics
- Expected value (coins, dice)
- Conditional probability
- Basic game theory decisions
Key Characteristics
- Negative marking for incorrect answers
- Skipping is often better than guessing
Preparation Tips
- Master basic probability models
- Develop quick estimation skills
- Use intuition alongside formulas
Zap-N (Cognitive Games)
This section tests reaction speed, attention, and mental endurance through multiple mini-games.
Game Types
- Reaction clicking
- Multi-task attention
- Spatial rotation
- Memory recall
Preparation Tips
- Practice similar cognitive tests beforehand
- Maintain focus across multiple rounds
- Avoid mental fatigue buildup
Coding (HackerRank)
Compared to earlier sections, this part is more standard and predictable.
Common Question Types (2025–2026)
- Order Matching / Simulation
- Stock price analysis (profit / volatility)
- Graph problems (shortest path, connectivity)
- Dynamic Programming
Preparation Tips
- Focus on LeetCode Medium-level problems
- Write clean and structured code
- Handle edge cases carefully
Preparation Strategy
Time Allocation
Suggested priority order:
- 80 in 8
- Zap-N
- NumberLogic / Probability
- Coding
It is often better to sacrifice some coding progress than to underperform in earlier sections.
Daily Practice Plan
- Daily mental math drills (core focus)
- Sequence + probability training
- 1–2 full mock simulations per week
Mindset
The biggest challenge of the Optiver OA is not difficulty — it is pressure.
- Extremely limited time
- Continuous high intensity
- Easy to lose focus mid-way
Consistency and composure often outperform raw intelligence in this assessment.
Final Thoughts
Optiver’s OA evaluates three core dimensions:
- Calculation speed (Mental Math)
- Thinking agility (Logic & Probability)
- Stress resilience (Zap-N)
Coding serves as the final validation layer rather than the primary filter.
If you are preparing for Optiver 26NG / Intern roles, this OA requires targeted preparation — standard algorithm practice alone is not enough.
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