Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not rounded numerals equals 24.

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

What type of tree can I carry in my hand?

In the figure that has been attached to this question, each digit represents a digit. The similar letters carry the same integer value. Can you expose the original digits?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

How can a man go eight days without sleep?

The dirtier I get, the whiter I look. Who am I?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

To tease, King Akbar told his most clever advisor Birbal to give his daughter one thing that she can eat when hungry, drink if she feels thirsty and can burn if she feels cold. King Akbar was shocked when Birbal gave Akbar's daughter one such thing that satisfies all of the above.

What did Birbal give to Akbar's daughter?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?