Unit Economics Math for Product and Growth Interviews
Mental math patterns for CAC, payback, margin, and LTV-style interview questions.
Last reviewed: 2026-03-04
Quick Answer
Frame each prompt as rate x volume or margin x retention, then compute with rounded assumptions and explicit units.
Why It Matters in Interviews
- Unit economics is common in PM, growth, and strategy interviews.
- Arithmetic errors can break otherwise strong business reasoning.
- Clear mental math keeps discussions focused on decisions.
Practice Drill Plan
- Practice CAC payback and gross margin scenarios daily.
- Use a 3-step template: define variables, compute, sanity-check.
- Explain each answer in one sentence with units.
Common Mistakes
- Mixing gross and net figures.
- Dropping units while calculating.
- Ignoring sensitivity when assumptions are uncertain.
Practice Now
Use these drills in short sessions and track your score/accuracy trend each week.