I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Replace the question mark with the correct number below.

A landlord calls both of his sons and tells them that their horses will now decide who will transfer the inheritance. He tells them to race along the land till the end and the one whose horse will be slower will win and be the heir to all the property.

Both of them keep wandering for days but to no result. Then they ask a wise man regarding it. The man advises them on the matter after which they jump on the horses and race as fast as they can till the end. Why did they do it?

What did the wise man say?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

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?

What kind of tree can you carry in your hand?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

Next Number in the Series,

5, 16, 49, 104, ?