System Design Workbench
Practice back-of-napkin math for estimating and planning large-scale systems. Work through 10 prompts per round, estimate quickly, and check your reasoning against reference answers.
64 / 2 to estimate values quickly.Made to be modified
This project is built for customization.
Use the bundled skills to add prompts or audit fairness of the question bank with Claude Code or Codex.
/add-questions [{TOPIC}]Have an agent research and add more questions
/audit-questions [--fix]Have an agent check the questions for math and fairness
Expression input supported. Try 1000 * 10 / 4.
Practice Round
Question text here
Review
Round Summary