Hacker News on 13 April 2009

• Teach Yourself Fundamentals of Math (Reasoning, Logic, Sets, Induction, Complex Numbers)
• Don’t use @import
• Things You Don’t Know About User IDs That Will Destroy You
• $80,000 for a Year Off? She'll Take It!
• Why is programming fun?
• Ebay Unacquires StumbleUpon
• Stop the Press: Building A Startup Presskit 101
• Ask HN: Feedback on Skritter, Learning Chinese with Spaced Repetition on App Engine
• Google's "Immigration Fixer"
• Ask HN: Startup PR - How could they get so many coverages?