Some of the answers I'm proud of:

• How to force update when doing git pull?
• How to get difference between two dates in Year/Month/Week/Day?
• https://math.stackexchange.com/questions/1091908/how-to-stop-forgetting-proofs-for-a-first-course-in-real-analysis/1092902#1092902
• https://math.stackexchange.com/questions/617625/on-familiarity-or-how-to-avoid-going-down-the-math-rabbit-hole/619259#619259
• https://academia.stackexchange.com/questions/7602/what-should-raise-red-flags-to-detect-fabricated-data/7609#7609
• https://tex.stackexchange.com/questions/109969/how-to-practice-latex/110002#110002

And an answer which I'm not particularly proud of, but which quite a few people seem to like:

• How to convert KeyValuePair to Dictionary as ToDictionary is not available in c#?