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

What Time Should the last watch show in the below figure?

Alex is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.

There are cliffs around the island, so he cannot jump off.

How can the Alex survive the fire? (There are no buckets or any other means to put out the fire)

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

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

Look at me. I can bring a smile to your face, A tear to your eye, Or even a thought to your mind. But, I can't be seen. What am I?

I have no life, but I can die. What am I?

What is full of holes but still holds water?

Decode below rebus
D
N
A
T
S , D

Who has married many women but was never married?