Instagram has 500 million DAU. 10% upload on a given day, 3 photos each. Every upload stores the 2 MB original plus three derived resolutions totaling another 4 MB — i.e. 6 MB stored per photo.
Use: 1 day = 86,400 sec ≈ 10^5 sec. Powers of 10: 1 KB = 10^3 B, 1 MB = 10^6 B, 1 GB = 10^9 B, 1 TB = 10^12 B, 1 PB = 10^15 B.
Compute daily uploads, daily storage, and 1-year storage.