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

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

What Word am I Looking For ?

Three ants are going up a hill, one behind the other. The last ant then says to the other ants, 'There is an ant behind me!'' How come?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

Fate has decided that you will only be pleased to meet me when you need me

Maybe that is why, when I am working, I start working

However annoying I may be to the regulars, the little ones are always inspired

I will always be waiting if you try to reach me

How many of you can guess my name, let me see

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

The more you take me, the more you leave me behind.
Who Am I?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?