Math Questions at Hashedin: What to Expect

Math questions at Hashedin aren't about advanced calculus—they test your ability to translate logical problems into efficient code. As a data-driven company, Hashedin values engineers who can model real-world scenarios, optimize resource usage, and handle edge cases with precision. These 3 questions (out of 32 total) assess your analytical thinking and clean implementation under constraints. If you neglect math prep, you risk failing early in the process.

What to Expect — types of problems

Problems typically fall into three categories. Number Theory questions involve prime numbers, divisors, GCD/LCM, or modular arithmetic. Combinatorics & Probability problems might ask you to count valid arrangements or calculate simple probabilities, often requiring careful reasoning to avoid double-counting. Mathematical Modeling is the most common: you'll be given a word problem (e.g., scheduling, distribution, or game simulation) and must derive a formula or iterative logic to solve it. Expect constraints that force an O(1) or O(log n) solution, not brute force.

How to Prepare — study tips with one code example

Focus on recognizing patterns. Practice deriving formulas for sums, sequences, and modular operations. Use brute force to verify your logic for small inputs before optimizing. A key pattern is using the GCD to solve problems about partitioning or cyclical events. For example, determining if two moving points meet involves checking if their cycle lengths align, which often reduces to a GCD condition.

def will_meet(a_step, b_step, total_positions):
    # Do they meet at the same position?
    # They meet if the distance between starting points is divisible by GCD of step sizes.
    from math import gcd
    g = gcd(a_step, b_step)
    # Example condition: they meet if (start_a - start_b) % g == 0
    # Here, assuming start at 0 and 1 for illustration:
    start_diff = 1
    return start_diff % g == 0

Recommended Practice Order

1. Master fundamentals: Practice GCD/LCM, prime checks, and modular arithmetic on platforms like LeetCode (tag "math").
2. Solve word problems: Translate descriptions into equations. Start with easy problems to build intuition.
3. Optimize for constraints: For each problem, find the O(1) formula. If stuck, work through small examples to spot patterns.
4. Time yourself: Simulate the interview: 10 minutes per math question is a good target.

Practice Math at Hashedin