We detected music and video encoded in radio signals from Alpha Centauri. We want to aim a large radio telescope there and blast them with something that's going to get their attention, something simple that shows we're intelligent. That header would be followed by complex information that would ...

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2024. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > So, the PSE Advent Calendar has only just started, but I have been puzzling non-stop already. You could say I'm al...

A couple did a couple of calculations, but lost the last one ... Can you recover the result? 345 53507 514 4914 ? Hint: (unhide if you want to see 4 possible options)

Turn something colorful into something white. Y E B L U L R E D O W ...

He said the house of his friend was in a long street, numbered on this side one, two, three, and so on, and that all the numbers on one side of him added up exactly the same as all the numbers on the other side of him. Funny thing that! He said he knew there was more than fifty houses on that sid...