📝 **Task:** Back-of-envelope capacity math — the first 30 seconds of every system-design round. You have **1,000,000 daily active users**. They read the feed **10×** per day on average, and they post **1×** per day (read:write = 10:1). **Write a function** \`writes_per_second(dau, posts_per_user_per_day)\` that returns the average writes/second, assuming load is spread evenly across 24 hours. Round to the nearest integer. Then call it with the numbers above and print the result. If you can't do this in your head, sysdesign rounds will feel like a math exam in a language you don't speak. Take a detour through Interview Prep iv-01..05 (Big-O + capacity) first. 📋 Implement the function above. Tests run automatically. 💡 **Hint:** Re-read the theory if you get stuck.