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Coinbase·Data Scientist·Online Assessment (OA)·Intermediate

Intermediate
Jul 2026

Summary

Coinbase Data Scientist aptitude screen, the timed kind where you have 50 questions and 15 minutes and basically have to triage on the fly. Mix of number sequences, pattern recognition, and grammar. Nothing conceptually hard but the clock is the whole challenge.

Questions Asked (3)

Q1

What is the next number in the sequence 3, 6, 12, 24, ___?

Algorithms & Data Structures
Author's notes

Each term doubles.

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AI HintsAI Generated

Suggested Approach

First, identify the pattern in the sequence by examining the relationship between consecutive terms. Then, apply the pattern to predict the next number. Finally, consider if there are alternative patterns and justify your choice.

Pro tip: For a Data Scientist role at Coinbase, go beyond the simple answer: discuss how you would validate the pattern with statistical methods or code, and mention the importance of recognizing geometric sequences in financial data.

1. Identify the pattern

Calculate the ratio or difference between consecutive terms to determine if the sequence is arithmetic, geometric, or follows another rule.

2. Apply the pattern

Use the identified rule to compute the next term. For example, if each term is double the previous, multiply the last term by 2.

3. Verify with alternative methods

Check if the pattern holds for all given terms and consider if other patterns (e.g., polynomial) could fit. Use code or mental math to confirm.

4. Communicate your reasoning

Explain your thought process clearly, including why you chose the pattern and how you arrived at the answer.

Key Points to Mention

  • Geometric sequence with common ratio 2
  • Exponential growth pattern
  • Relevance to financial data and compound interest
  • Use of Python or R to quickly identify patterns
  • Importance of validating assumptions in data science
  • Clear communication of logical steps

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

Q2

A repeating symbol pattern (triangle, square, circle) cycles in order. Which symbol appears in the 10th position?

Algorithms & Data Structures
Author's notes

10 mod 3 gives you 1, so it's the first symbol in the cycle, the triangle.

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AI HintsAI Generated

Suggested Approach

Recognize that the pattern repeats every 3 symbols, so use modular arithmetic to find the position within the cycle. Compute (10-1) mod 3 to get the index (0-based) and map it to the symbol.

Pro tip: While the answer is straightforward, mention that this is a classic example of periodic patterns and modular arithmetic, which are fundamental in time series analysis and signal processing—skills highly relevant for a data scientist at Coinbase.

1. Identify the repeating unit

Determine the sequence of symbols in one cycle: triangle, square, circle. Note that the cycle length is 3.

2. Determine the position within the cycle

For the 10th position, compute (10-1) mod 3 = 0, which corresponds to the first symbol in the cycle (triangle). Alternatively, 10 mod 3 = 1, which also maps to the first symbol if using 1-based indexing.

3. Map to the symbol

Using the remainder, identify the symbol: remainder 0 (or 1) -> triangle, remainder 1 (or 2) -> square, remainder 2 (or 0) -> circle. Thus, the 10th symbol is triangle.

4. Verify with a quick mental check

List the first few positions: 1: triangle, 2: square, 3: circle, 4: triangle, 5: square, 6: circle, 7: triangle, 8: square, 9: circle, 10: triangle. Confirm the answer.

Key Points to Mention

  • Modular arithmetic and its role in periodic patterns
  • Cycle length and how to compute it
  • 0-based vs 1-based indexing and how to avoid off-by-one errors
  • Application to time series analysis (e.g., seasonality detection)
  • Generalization to any position n: symbol = cycle[(n-1) mod 3]
  • Efficiency of O(1) solution vs naive iteration

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

Q3

Fill in the blank: 'She postponed the launch because she ____ the data were incomplete.' Choose the correct verb form from the options given.

Adaptability & Ambiguity
Author's notes

Answer is 'realised', past tense to match the rest of the sentence.

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AI HintsAI Generated

Suggested Approach

First, identify the grammatical subject and the time relationship between the postponement and the incompleteness of the data. Then, evaluate each verb option for tense, aspect, and subject-verb agreement, selecting the one that logically explains the reason for the postponement. Finally, confirm your choice by mentally substituting it into the sentence to ensure it sounds natural and precise.

Pro tip: In professional settings, especially at data-driven companies like Coinbase, precision in language reflects precision in analysis. Pay attention to subtle distinctions like 'were' vs. 'are' to show you understand the timeline of events and can communicate clearly under ambiguity.

1. Identify the subject and timeline

Determine that 'she' is the subject and that the postponement happened in the past. The data's incompleteness likely occurred before or at the time of postponement.

2. Analyze verb tense and aspect

Consider whether the verb should be simple past, past perfect, or another form. The blank requires a verb that indicates a past state of the data.

3. Check subject-verb agreement

Ensure the verb agrees with 'data' (plural in formal usage) or 'she' if the verb is transitive. The correct form must match the subject.

4. Evaluate each option

Test each provided option by inserting it into the sentence. Eliminate those that are grammatically incorrect or semantically illogical.

5. Confirm and justify

Select the best option and be prepared to explain why it is correct, referencing grammar rules and contextual meaning.

Key Points to Mention

  • Subject-verb agreement: 'data' is plural in formal English, so 'were' is correct.
  • Tense consistency: the postponement is in the past, so the reason should also be in the past.
  • Logical sequence: the data were incomplete at the time she made the decision to postpone.
  • Distinction between 'were' and 'are': 'are' would imply the data are still incomplete, which may not be the intended meaning.
  • Avoidance of 'was': 'was' would incorrectly treat 'data' as singular.
  • Clarity and precision in communication, especially in data science contexts.

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