Estimation question

How many daily active users does Slack have?

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

Whether the candidate can build a reasonable estimate for a specific known product using public context and a clear breakdown.

Anchor on any known context, for example Slack's reported user base being in the tens of millions of daily active users, and state this as an assumption.
Break it down: total registered organizations using Slack, average team size, and the percent of registered users who are daily active versus occasional.
Assume roughly 20 to 25 million daily active users based on general knowledge of Slack's scale at a mature stage.
Sanity check against comparable tools (Microsoft Teams, Zoom) to see if the number is in a plausible range for a widely used workplace tool.
Present the number as an estimate with a stated range, not a falsely precise figure.

Anchors on general knowledge of Slack's scale and states it clearly as an assumption rather than presenting it as fact.
Uses a comparable product to sanity check the plausibility of the final number.
Gives a range instead of one falsely precise figure.

Presenting a memorized statistic as certain fact without framing it as an estimate.
Skipping the sanity check against comparable products.

How would you estimate this differently if you had zero prior knowledge of Slack's public numbers?
What would explain a large gap between weekly and daily active users for a work tool like this?