The centre of the third figure is empty. What digit should fit inside?

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

I’m tall when I’m young, and I’m short when I’m old. What am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

What month of the year has 28 days?

There are two beautiful yet remote islands in the South Pacific. The Islanders born on one island always tell the truth, and the Islanders from the other island always lie.
You are on one of the islands and meet three Islanders. You ask the first which island they are from in the most appropriate Polynesian tongue, and he indicates that the other two Islanders are from the same island. You ask the second Islander the same question, and he also indicates that the other two Islanders are from the same island.
Can you guess what the third Islander will answer to the same question?

A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.

How did the man in the booth know to give him two tickets without even looking at him?

Can you start the fire using two pieces of wood?