Code challenges and puzzles

Can you solve these code puzzles? For everyone who dares to think outside the box. And if you like a competitions, climb the leaderboard in ranked and become the best.

Do your best to solve these programming challenges and puzzles. Even if you don't know anything about computer code, learn the ropes through trial and error.

The best way to solve these puzzles is by using a pen and paper, calculators and spreadsheets are allowed as well. You can cheat if you want but you'll probably not learn much by doing so.

If you're a beginner start with the easy ones and work your way up. Don't give up if get you're stuck, but make use of your resources to find the answers (Google it). If you already have some coding knowledge you will still find these puzzles quite a challenge. Try completing all of them without cheating by running the code somewhere.