Clever riddles with simple answers

You will throw me away when you want to use me. You will take me in when you don’t want to use me. What am I?

I have more than 80 keys, but I cannot open any lock. What Am I?

I don’t have eyes, ears, nose and tongue, but I can see, smell, hear and taste everything. What am I?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

I run over fields and woods all day. Under the bed at night I sit, never alone. My tongue hangs out, up and to the rear, waiting to be filled in the morning. What am I?

Which is the rope you never skip with?

I drift forever with the current down these long canals they've made. Tame, yet wild, I run elusive, multitasking to your aid. Before I came, the world was darker. Colder, sometimes, rougher, true. But though I might make living easy, I'm good at killing people too.

What runs around the house, but does not move?

Armored but not a knight, snapping but not a twig, and always at home, even on the move. What am I?

It’s been around for millions of years, but it’s no more than a month old. What is it?