Actually the puzzles aren't as difficult as they appear at first. True, a bit annoying, but once you get the hang of it it can be done. The matching pictures in pairs is the only one that can confuse you because there is one picture without a pair. The sliding puzzle used to have a time limit on it, so now that it hasn't, you can just take it slow, and there are only a few ways you can slide the pieces, so it will fall into place. And if you pay attention while playing, answering the questions should be a breeze.
And where was a 5-digit code? I don't remember that one. There are a lot of 4-digit codes, though.