Guesstimates Example 3 - Estimate the Number Queries Answered by Google Per Second

Clarifying Questions:

Before solving, the candidate asks three clarifying questions:

1. Should the estimate include only Google Search or other Google platforms like Gmail, YouTube, and Maps?

• Interviewer: Only Google Search.

2. Should the estimate focus on specific devices (mobile/desktop)?

• Interviewer: All devices.

3. Is the focus on a specific region or global?

• Interviewer: Global.

Problem Statement:

Estimate the number of Google search queries per second across all devices, globally.

Approach & Assumptions:

1. Global Population: ~7.5 billion

2. Internet Penetration: ~70%

3. Google Market Share: ~80%

4. Non-Google Regions: Countries like China and Russia (~1.5 billion people) where Google usage is restricted or low.

• Effective user base: (7.5B - 1.5B) * 70% * 80% = ~3 billion Google users

5. Search Behavior: Using the 80/20 rule

• Top 20% of users generate 80% of searches.

• Assuming each of these heavy users performs ~15 searches/day:

• 20% of 3B = 0.6B users

• 0.6B users * 15 searches = 9B searches/day (80% of total)

• Total daily searches = 9B / 0.8 ≈ 11.25–12B

6. Final Calculation:

• Daily searches ≈ 12B

• Seconds per day = 86,400

• Searches per second = 12B / 86,400 ≈ 140,000 searches per second

Conclusion:

Estimated number of Google search queries answered per second globally is approximately 140,000.

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