← Optiver Interview Insights

Optiver·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Optiver software engineer interview had a mental math and pattern recognition section that felt more like a trading firm aptitude test than a typical coding screen. No calculator, no hints, just you and the sequences under pressure.

Questions Asked (4)

Q1

Find the next number in the sequence: 3, 6, 12, 24, ?

Algorithms & Data Structures
Author's notes

This one was fine.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by examining the sequence for simple patterns: differences, ratios, or operations. Notice each term is double the previous, so the next term is 48. Then discuss the pattern's properties and potential edge cases to show depth.

Pro tip: At Optiver, interviewers value clear, logical reasoning over just the answer. Verbalize your thought process step-by-step, and mention that such sequences can have multiple valid continuations depending on the rule, but the simplest is geometric doubling.

1. Identify the pattern

Look at the relationship between consecutive terms. Check differences (3, 6, 12, 24) and ratios (2, 2, 2).

2. Determine the rule

Recognize that each term is multiplied by 2 to get the next term. This is a geometric sequence with common ratio 2.

3. Apply the rule

Multiply the last term (24) by 2 to get the next term: 48.

4. Verify and discuss

Check that the rule holds for all given terms. Mention that other patterns (e.g., adding increasing powers of 2) could also fit, but the simplest is doubling.

Key Points to Mention

  • Geometric sequence with common ratio 2
  • Exponential growth pattern (powers of 2 times 3)
  • Alternative interpretations (e.g., differences are 3, 6, 12, which double)
  • Importance of simplicity and Occam's razor in pattern recognition
  • Relevance to algorithmic thinking and sequence prediction
  • Clear communication of reasoning process

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

Find the next number in the sequence: 2, 3, 5, 7, 11, ?

Algorithms & Data Structures
Author's notes

Prime numbers.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, identify the pattern in the sequence. Notice that the numbers are prime numbers, so the next number is the next prime after 11, which is 13. Then, consider alternative patterns and explain why the prime number pattern is the most plausible.

Pro tip: At Optiver, interviewers value clear reasoning and the ability to consider multiple hypotheses. Even if you recognize the pattern quickly, briefly mention other possibilities and why they are less likely, demonstrating thoroughness.

1. Observe the sequence

List the given numbers: 2, 3, 5, 7, 11. Look for common properties such as parity, divisibility, or known sequences.

2. Identify the pattern

Recognize that all numbers are prime. Verify that each number has no divisors other than 1 and itself.

3. Determine the next term

Find the next prime number after 11. Check 12 (not prime), 13 (prime), so the next number is 13.

4. Consider alternative patterns

Briefly explore other possible patterns (e.g., differences, Fibonacci-like) and explain why they don't fit as well as the prime sequence.

5. State your answer with reasoning

Conclude that the next number is 13, and summarize the reasoning that the sequence consists of consecutive prime numbers.

Key Points to Mention

  • The sequence consists of prime numbers.
  • Prime numbers are natural numbers greater than 1 with no positive divisors other than 1 and themselves.
  • The next prime after 11 is 13.
  • Alternative patterns such as arithmetic progression or Fibonacci do not fit the given sequence.
  • Demonstrate systematic problem-solving by checking divisibility of candidate numbers.
  • Communicate your thought process clearly, as interviewers assess reasoning, not just the final answer.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q3

Find the next number in the sequence: 1, 4, 9, 16, ?

Algorithms & Data Structures
Author's notes

Perfect squares, answer is 25.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, identify the pattern by checking differences between consecutive terms: 3, 5, 7, which are consecutive odd numbers. Then, recognize that the sequence consists of perfect squares (1^2, 2^2, 3^2, 4^2), so the next term is 5^2 = 25. Finally, articulate your reasoning clearly and consider alternative patterns to demonstrate thoroughness.

Pro tip: At Optiver, interviewers value not just the correct answer but also your ability to explain your thought process and handle ambiguity. Mention that while the pattern is likely perfect squares, you would verify with additional terms if available, showing scientific rigor.

1. Examine the sequence

Look at the given numbers: 1, 4, 9, 16. Notice they are all perfect squares of consecutive integers starting from 1.

2. Identify the pattern

Confirm the pattern: 1=1^2, 4=2^2, 9=3^2, 16=4^2. The next term should be 5^2.

3. Compute the next term

Calculate 5^2 = 25. This is the most straightforward answer based on the identified pattern.

4. Consider alternative patterns

Check if other patterns fit, such as differences (3,5,7, next difference 9 gives 25) or polynomial fits. This shows robustness in reasoning.

5. Communicate your answer

State the answer clearly (25) and explain the reasoning, including why you chose that pattern over others.

Key Points to Mention

  • Perfect squares: 1^2, 2^2, 3^2, 4^2, so next is 5^2 = 25.
  • Differences between terms: 3, 5, 7, which are consecutive odd numbers; next difference is 9, leading to 25.
  • The sequence can be generated by n^2 for n=1,2,3,4,...
  • Mention that with only four terms, multiple patterns could fit, but the simplest is perfect squares.
  • If asked for a general term, it's a_n = n^2.
  • Demonstrate awareness of potential ambiguity and how to resolve it by seeking additional context.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q4

Find the next number in the sequence: 1, 2, 4, 7, 11, 16, ? and also describe your fallback strategy if you can't immediately spot the pattern in any of these.

Algorithms & Data StructuresAdaptability & Ambiguity
Author's notes

The differences are 1, 2, 3, 4, 5 so the next difference is 6, giving you 22.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, compute the differences between consecutive terms to see if a simple pattern emerges. If the differences are not constant, look at second differences or other common patterns (e.g., squares, primes). If no pattern is immediately obvious, systematically test common sequences and be prepared to discuss your reasoning and fallback strategies.

Pro tip: At Optiver, they value not just the answer but your thought process and how you handle uncertainty. Verbalize your reasoning clearly and if you're stuck, propose a reasonable fallback like assuming a polynomial pattern or asking clarifying questions.

1. Compute differences

Calculate the differences between consecutive terms: 2-1=1, 4-2=2, 7-4=3, 11-7=4, 16-11=5. The differences are 1, 2, 3, 4, 5, so the next difference is likely 6.

2. Identify pattern

The differences increase by 1 each time, indicating a quadratic sequence. The next term is 16 + 6 = 22.

3. Verify with second differences

Check second differences: 2-1=1, 3-2=1, 4-3=1, 5-4=1. Constant second difference confirms a quadratic pattern.

4. Fallback strategy

If no pattern is apparent, try common sequences (Fibonacci, primes, squares, etc.), consider polynomial fits, or ask if there are additional constraints. State your assumptions and reasoning.

Key Points to Mention

  • Difference method for sequence analysis
  • Second differences and quadratic sequences
  • Systematic testing of common patterns (arithmetic, geometric, Fibonacci, primes, squares)
  • Fallback: assume polynomial of degree n and solve for coefficients
  • Importance of verbalizing thought process and handling ambiguity
  • Optiver's focus on problem-solving and adaptability

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.