A garden is divided into equal squares. Two snails start at S and follow its perimeter in opposite directions, at 1 m/h and 2 m/h as indicated. Where do they first meet?
All the bulbs in the network are initially off. Touching a bulb lights it and every bulb directly connected to it. What is the smallest number of bulbs that must be touched to light them all?
A lion is behind one of three doors. Door 1 says “The lion is not behind this door”; door 2 says “The lion is behind this door”; door 3 says “Two plus three is five.” Exactly one statement is true. Where is the lion?
Eva and Olga are girls; Adam, Isaac and Urban are boys. A girl throws the ball to the other girl or a boy. A boy throws to another boy, but not back to the boy who just threw to him. Eva makes the first throw to Adam. Who makes the fifth throw?
On Monday Alexandra shares a picture with 5 friends. Every new recipient sends it the next day to two new friends who have not seen it. On which day does the total number of people who have seen it first exceed 100?
Four ladybugs occupy a 4×4 grid. One sleeps and stays fixed. At each whistle the other three move to free edge-neighbouring cells, without immediately returning to their previous cells. The first four positions are shown. Which option can follow the fourth whistle?