LinkedIn has 900 million registered users. In any given hour, 1% are active, and each active user processes (accepts/declines) 5 connection requests per hour.
Use: 1 hour = 3,600 sec. 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 hourly volume, average QPS, and lunch-hour peak.