If eleven plus two equals one, what does nine plus five equal?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

Which five letter word can be added at the end of below word to form a
valid word?

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Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

What animal walks on four legs in the morning, two legs during the day, and three legs in the evening?

Oedipus, the king of Thebes, figured out the answer to the riddle:

Why do people go to bed?

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?

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

Rearrange the letters in "new door" to make one word.