Estimation question

If you want to build the world's most popular mobile messaging product, how would you estimate how much network bandwidth would be used in a year?

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What this question tests

Advanced estimation combining user scale, usage patterns, and technical data unit conversion.

Clarify scope: define what counts, text messages, voice notes, images, and video shared through the app over a year.
Estimate the user base for a world-leading messaging app, roughly 2 billion monthly active users (assumption).
Break usage into message types and estimate daily volume per type: mostly small text messages, with a smaller share of images and voice notes which are far larger in size.
Estimate average data size per type: text near-negligible, images roughly 200 KB to 1 MB, voice notes roughly 500 KB to a few MB.
Estimate daily messages per user by type, then multiply by user count and average size per type to get daily bandwidth, then multiply by 365 for the year.
Sum across types and sanity check the order of magnitude, landing in the range of tens of exabytes per year given billions of users sharing rich media daily.

Breaks bandwidth by message type instead of treating all messages as equal size, since images and voice notes dominate total bytes despite being a smaller share of message count.
States clear per-type size and volume assumptions before combining them (assumption).
Sanity checks the final magnitude against known internet traffic scale, landing in the exabyte range for a billion-plus user app.

Treating all messages as equal size, wildly understating bandwidth from media-heavy content.
No unit conversion shown between KB, MB, and eventual exabyte-scale totals.
Skipping the media message types entirely and only estimating text volume.

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