I have feet, but no legs. Which animal Am I?

Find out the missing number in the picture attached:

What has no start, end, or centre?

Two friends were stuck in a cottage. They had nothing to do and thus they started playing cards. Suddenly the power went off and Friend 1 inverted the position of 15 cards in the normal deck of 52 cards and shuffled it. Now he asked Friend 2 to divide the cards into two piles (need not be equal) with equal number of cards facing up. The room was quite dark and Friend 2 could not see the cards. He thinks for a while and then divides the cards in two piles.

On checking, the count of cards facing up is same in both the piles. How could Friend 2 have done it ?

A newspaper is supposed to have 60 pages, but pages 24 and 41 are missing.
Which other pages won't be there?

When a clock is observed, the hour hand is at a minute mark and the minutes hand is six minutes ahead of it.

When the clock is observed again after some time, the hour hand is precisely on a different minute mark and the minute hand is seven minutes ahead of it.

Can you calculate how much time has elapsed between the two observations?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

A bomb goes off.
Carnage.
One person, only a few feet away, survives! How can this be?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?