← Google Interview Insights

Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Fermi estimation question at Google, classic stuff. One question, no real context given about the role or outcome.

Questions Asked (1)

Q1

How many quarters would you need to stack to match the height of the Empire State Building?

Adaptability & AmbiguityProduct Analytics & Metrics
Author's notes

These estimation questions always feel deceptively easy until you're actually doing the math out loud.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Break the problem into two parts: estimate the height of the Empire State Building and the thickness of a quarter, then divide. Clearly state your assumptions and round to make the math easy, focusing on demonstrating logical reasoning rather than getting the exact number.

Pro tip: Interviewers care more about your thought process than the final number. Verbalize your assumptions and sanity-check your answer (e.g., 'Does 3 million quarters seem reasonable?') to show you can handle ambiguity and validate your work.

1. Clarify the question

Confirm what 'match the height' means (e.g., stack height equals building height) and whether to include the antenna. Ask if you should assume standard quarter thickness.

2. Estimate the height of the Empire State Building

Recall or estimate the building's height. A common figure is about 1,250 feet to the roof, or 1,454 feet including the antenna. Choose one and state it.

3. Estimate the thickness of a quarter

A quarter is about 1.75 mm thick. Convert this to feet (approximately 0.00575 feet) or convert the building height to millimeters for easier division.

4. Calculate the number of quarters

Divide the building height by the quarter thickness. For example, 1,250 feet / 0.00575 feet ≈ 217,000 quarters. Round to a sensible number.

5. Sanity-check and conclude

Verify the answer makes sense: 217,000 quarters is about $54,250 in quarters, which seems plausible. State your final answer with the assumptions made.

Key Points to Mention

  • Clearly state assumptions (e.g., building height to roof vs. antenna, quarter thickness).
  • Use unit conversion correctly (feet to millimeters or vice versa).
  • Round numbers to simplify calculations and avoid false precision.
  • Sanity-check the final answer for reasonableness.
  • Acknowledge that the exact number isn't critical; the approach is what matters.
  • If time permits, mention alternative methods (e.g., using a known reference like a person's height).

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