Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

What is black when you buy it, red when you use it, and gray when you throw it away?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

What is always in front of you but can’t be seen?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

On a special event at the prison, 5 prisoners John, Jacob, Krist, Tang, and Dang given a chance to go to a sauna and can bring one thing with them.

Following are the things that the prisoners bring with them.
John: A soda
Jacob: Thermos
Krist: Book named "How to kill"
Tang: A Walkman
Dang: Harmonica

Since it is a Sauna, no one can see each other. After a while When the steam is switched, Tang was found dead and there was blood all around.
J Bond was called and he instantly come to know who can be the murderer. How?