What is the next number in this matchsticks series riddle?

15 caves are arranged in a circle at the temple of doom. One of these caves has the treasure of gems and wealth. Each day the treasure keepers can move the treasure to an adjacent cave or can keep it in the same cave. Every day two treasure seekers visit the place and have enough time to enter any two caves of their choice.

How do the treasure seekers ensure that they find the treasure in the minimum number of possible days?

In the following picture, E is going to slide the object down and as per the terrain and the physics, the round object is going to travel all the way till the end. Now, can you analyze who all people will die when it happens?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

How many letters are in the alphabet?

What work can one never finish?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

Who is that with a neck and no head, two arms and no hands? What is it?

Identify the hidden meaning behind this picture?

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