SIG OA Answers: The Complete 2027 Quantitative Evaluation Guide (with Solutions)

Just got invited to the 2027 SIG Quantitative Evaluation (the SIG OA)? Or trying to figure out what's actually on it before you apply? You're in the right place. This guide walks through every section of the SIG OA, gives you real sample questions with full answers and worked solutions, and tells you exactly how to prepare so you actually pass.

We've helped students land offers at SIG, Jane Street, Citadel Securities, Optiver, IMC, DRW, Five Rings, and more. The patterns in the SIG OA don't change much year over year — once you've drilled them, the test goes from "panic mode" to "comfortable."

What Is the SIG Quantitative Evaluation?

SIG (Susquehanna International Group) is one of the world's largest market-making firms, with a particular edge in options trading. They hire across Quant Trading, Quant Research, Quant Analyst, and Quant Developer roles, and almost every one of those tracks starts with the SIG OA — an online assessment delivered through HackerEarth or a similar platform.

The OA is the gatekeeper. SIG receives tens of thousands of applications and uses the OA to cut the pool down to a few hundred before any human ever reads your resume. The bar is real — top candidates routinely fail it because they didn't know what to expect.

Here's exactly what's on it.

The 4 Sections of the SIG OA (and How to Beat Each One)

1. Sequences (Number Series)

You're given a sequence of 4–6 numbers and asked for the next term. Time pressure is brutal — usually ~30 seconds per question. Patterns include:

• Arithmetic / geometric progressions
• Differences-of-differences (2nd-order patterns)
• Alternating sub-sequences ("odd terms do X, even terms do Y")
• Multiplicative + additive combos (e.g. a_{n+1} = 2*a_n + 3)
• Prime gaps, squares, Fibonacci variants, factorials

Sample question: What comes next? 2, 6, 12, 20, 30, ?

Answer: 42. The differences are 4, 6, 8, 10, so the next difference is 12. 30 + 12 = 42. (Equivalently, the formula is n(n+1) starting from n=1.)

Sample question: What comes next? 1, 2, 6, 24, 120, ?

Answer: 720. These are factorials — each term is the previous times an incrementing integer (×2, ×3, ×4, ×5, ×6).

Sample question: What comes next? 3, 7, 16, 35, 74, ?

Answer: 153. Each term follows a_{n+1} = 2*a_n + n. Verify: 2*3+1=7, 2*7+2=16, 2*16+3=35, 2*35+4=74, 2*74+5=153. ✓

How to beat it: the first move on every sequence question is write the differences. If they don't reveal a pattern, write the ratios. If neither works, check if odd/even terms form their own sub-sequences. 80% of SIG sequence problems fall to one of those three checks.

2. Mental Math

Pure arithmetic under time pressure: percentages, fraction operations, multi-digit multiplication, divisions, square roots, conversions. Usually ~15 seconds per question and no calculator.

Sample question: 17 × 23 = ?

Answer: 391. Use the difference-of-squares trick: 17 × 23 = (20-3)(20+3) = 400 - 9 = 391.

Sample question: 38% of 250 = ?

Answer: 95. Convert: 38% of 250 = 25% of 380 = 380/4 = 95. (Swap the percentage trick — it's almost always faster.)

Sample question: √4096 = ?

Answer: 64. Memorize the powers of 2 up to 2^16 = 65536; then 4096 = 2^12 = (2^6)^2 = 64^2.

How to beat it: memorize squares up to 30², powers of 2 up to 2^16, common fraction-to-decimal conversions (1/7 = 0.142857..., 1/9 = 0.111..., etc.), and drill the swap-the-percentage trick. There are only ~10 mental-math tricks worth knowing, and every SIG question rewards one of them.

3. Pattern Recognition

Visual or numeric — the "find the next shape" or "which of these doesn't belong" style. SIG mixes in matrix-style patterns (3×3 grid, find the missing cell) and analogy patterns (A:B :: C:?).

How to beat it: for matrices, check rows first, then columns, then diagonals — usually the pattern lives in one of those three. For analogies, identify the transformation applied to A→B, then apply the same transformation to C.

4. Probability & Expected Value

This is the section that separates good candidates from elite ones, and where most people without quant prep fail. Topics:

• Coin / die / card probability
• Conditional probability (Bayes-style setups)
• Expected value calculations
• Simple combinatorics

Sample question: You flip 3 fair coins. What's the probability of getting exactly 2 heads?

Answer: 3/8. There are 2³ = 8 equally likely outcomes. Exactly 2 heads happens in C(3,2) = 3 of them (HHT, HTH, THH). So 3/8.

Sample question: A bag has 3 red and 5 blue balls. You draw 2 without replacement. What's the probability both are red?

Answer: 3/28. P(both red) = (3/8) × (2/7) = 6/56 = 3/28.

Sample question (EV — common SIG style): A game costs $5 to play. You roll a fair die; if it shows a 6, you win $25. Otherwise nothing. Should you play?

Answer: No. EV = (1/6)(25) + (5/6)(0) − 5 = 25/6 − 5 = 25/6 − 30/6 = −5/6 ≈ −$0.83 per game. Negative EV — don't play.

Sample question (conditional — trickier): You have two coins: one fair, one with two heads. You pick one at random and flip it — it lands heads. What's the probability you picked the two-headed coin?

Answer: 2/3. Bayes: P(2H | H) = P(H | 2H) P(2H) / P(H) = (1)(1/2) / [(1)(1/2) + (1/2)(1/2)] = (1/2) / (3/4) = 2/3.

How to beat it: drill expected value, conditional probability, and basic combinatorics (C(n,k), P(n,k)) until they're automatic. Bayes' Theorem appears on almost every SIG OA in some form — know it cold.

Format, Scoring, and What "Passing" Looks Like

• Length: typically 60–90 minutes, ~50–80 questions across the four sections.
• Negative marking: YES. Wrong answers cost you points. Skipping is often better than guessing unless you can eliminate at least one option.
• Adaptive: some years have used adaptive difficulty (correct answers → harder questions). Don't panic if your questions feel impossibly hard mid-test — that means you're doing well.
• Bar: SIG doesn't publish a cutoff, but in practice, you need to be in roughly the top 5–10% of test-takers to move on. That means ~75–85% accuracy across all sections.

The Single Biggest Mistake Candidates Make

Spending too long on any one question. Every minute you burn on a hard sequence is a minute you lose on three easy mental-math points. Skip aggressively and come back if there's time. The OA rewards throughput, not perfection.

How to Actually Prepare for the SIG OA in 2027

Honest answer: you can't grind the SIG OA the night before. The candidates who pass have been drilling these exact question types — sequences, mental math, EV, conditional probability — for weeks or months.

That's the gap Quant Blueprint closes. Our team includes current and former SIG Quant Traders who built the program around the exact patterns SIG tests for. Enrolling gets you:

• SIG OA Question Bank — hundreds of practice problems modeled on real SIG OAs, organized by section (sequences, mental math, probability, EV)
• Full Answer Key with Worked Solutions — every problem solved step-by-step, with the intuition behind it (not just the final number)
• 16+ Hours of Video Lectures — taught by SIG/Jane Street/Citadel quants, covering every probability concept the OA tests
• Phone Interview + Onsite Question Bank — for when you pass the OA (and you will), the next stages are covered too
• 1:1 Resume Tailoring — so the OA isn't your only shot at SIG; we'll also get you interviews at Jane Street, Citadel, Optiver, IMC, and DRW

Our students have landed offers at every major quant firm — see the unedited screenshots of the emails they sent us when they got the call.

Ready to Pass the SIG OA?

Book a free call and we'll walk you through the program, show you exactly what's in the question bank, and tell you honestly whether we can get you to the SIG offer.

Don't roll the dice on the OA. Prepare like the people who pass do.