M9 · Sizing & Estimation

B-tree lookups per second on a hard disk

• 4:00 on the clock

  The clock is the server's. It starts when you press start, survives a reload, and answers after it are refused.

• No hints, no autocomplete

  One answer, locked in when you submit, the way it is when you say it out loud.

• Debrief afterwards

  When it ends you get the answer, the reasoning, and where the curriculum teaches it.