Thirty €1 coins are arranged in a circle on a table. Ten of these coins are fake and a little lighter than the 20 real coins. You don’t know where in the circle the fake coins are, but you have been ...

It's the first brain teaser in our brand-new series! Finding the solution will take some mental muscle, but you're up for the challenge. Reading time 2 minutes Welcome to the first Gizmodo Monday ...

Seven coins have been placed in the “H” shape above. Altogether there are five lines of three, including the diagonals. Your challenge is to place two more coins so that you can make 10 straight lines ...