Estimation question

How many apps are in the Apple App Store or Android Playstore?

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Tests estimation using a supply-side approach (developer output) rather than guessing a headline number directly.

Choose an approach: estimate via number of active developers and average apps published per developer, rather than guessing the store total directly.
Assume roughly 20 million registered app developers globally across both platforms combined, based on known developer program scale.
Assume an average of 1.5 to 2 apps published per active developer, accounting for many one-off or abandoned apps alongside prolific publishers.
Multiply: 20 million developers times roughly 1.75 apps per developer gives approximately 35 million total apps across both stores.
Sanity-check by comparing to publicly known figures (each major store has historically reported roughly 2 to 3.5 million live apps) and reconcile the gap by noting many apps are removed or inactive over time.

Uses a supply-side estimation method (developers times apps per developer) instead of guessing the final number outright.
Explicitly reconciles the estimate against known public figures and explains the gap (delisted, abandoned, or duplicate apps), showing critical self-checking.
States assumptions clearly, e.g. 'assume 1.75 apps per active developer', so each link in the logic is inspectable.
Distinguishes cumulative apps ever published from currently live apps, since the question could mean either.

Quoting a remembered headline number without showing any derivation.
Not distinguishing between total apps ever published and currently live apps in the store, which are very different numbers.

How would your estimate change if you accounted for app removal rates over time?
Which of your assumptions has the widest error range, and why?