// QUANT INTERVIEW PREP
Number Sequence Quant Interview Prep & Practice
Sequence questions appear on numerical reasoning screens at most market makers. Each one hides a rule; the skill is finding it quickly.
Sample Number Sequence Questions
Question 1 · Optiver Trading Assessment
-11, -3, 6, 16, 27, ?
See the solution ↓Question 2 · SIG Problem-Solving Assessment
What comes next: 3, 4, 9, 12, 15, 36, ...?
See the solution ↓Question 3 · Optiver Trading Assessment
-7, 0, 8, 17, 27, ?
See the solution ↓Question 4 · SIG Problem-Solving Assessment
What comes next: 3, 6, 11, 20, 37, 70, ...?
See the solution ↓Question 5 · Optiver Trading Assessment
-2, 82, 0, 62, 2, ?
See the solution ↓
Step-by-Step Solutions
Solution 1
-11, -3, 6, 16, 27, ?
Answer: 39
First differences increase by 1 each time, forcing the sequence to cross zero.
Solution 2
What comes next: 3, 4, 9, 12, 15, 36, ...?
Answer: 21
Two sequences are interleaved. The 1st, 3rd and 5th terms add 6 each time (3, 9, 15), and the 2nd, 4th and 6th multiply by 3 (4, 12, 36). The next term belongs to the arithmetic one: 15 + 6 = 21.
Solution 3
-7, 0, 8, 17, 27, ?
Answer: 38
First differences increase by 1 each time, forcing the sequence to cross zero.
Solution 4
What comes next: 3, 6, 11, 20, 37, 70, ...?
Answer: 135
The k-th term is 2^k + k: 2^1+1=3, 2^2+2=6, 2^3+3=11, 2^4+4=20, 2^5+5=37, 2^6+6=70. Next is 2^7 + 7 = 128 + 7 = 135.
Solution 5
-2, 82, 0, 62, 2, ?
Answer: 42
Interleaved sequences: odd positions rise slowly from near zero, evens drop rapidly.
How to Pass the Number Sequence Screen
Take differences first, then ratios. Most sequences are arithmetic, geometric or one of those applied to the gaps.
Look for two interleaved sequences. Odd and even positions often follow separate rules.
Keep a short list of usual suspects: squares, cubes, primes, Fibonacci and factorials cover a large share of the questions.
Practice number sequence alongside 4,000+ more procedurally generated scenarios under live timer conditions. Unlock Outcry Pro.
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