Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works
← Challenges 📅 Daily medium

spot the cr slip

Playing as a guest — your score won't be saved. Log in to keep it.

This checks the Cauchy–Riemann equations for u and v at a point — but one line is wrong. Click the FIRST line where the reasoning breaks.

Found it! points.

Not quite — line was the first mistake.

+ XP

Next → Back to Challenges