Can you convert the number zero(0) into a positive number using just one mathematical operator ?

I know a 5-digit number having a property that With a 1 after it, it is three times as large as it would be with a one before it.

Guess the number?

A man started to town with a fox, a goose, and a sack of corn. He came to a stream which he had to cross in a tiny boat. He could only take one across at a time. He could not leave the fox alone with the goose or the goose alone with the corn. How did he get them all safely over the stream?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

'S' refers to the number of seconds in a day and 'H' refers to the number of hours in ten years. Which quantity out of these two is greater?

I’m orange, I wear a green hat and I sound like a parrot. What am I?

Can you find out which options fits best with the missing column?