When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

What is the Surname of Barbie Doll?

How many times can you subtract the number two from the number fifty?

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

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

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

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

In an interview, a boy was asked an unusual question 'How two persons sitting with a table in between them can't see each other?' He was unable to reply. Can you?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?