I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

Replace the question mark with the correct number.

The more of this there is, the less you see. What is it?

A non-stop marathon is the shared favourite sport of three brothers.

*The oldest one is fat and short and trudges slowly on.
*The middle brother's tall and slim and keeps a steady pace.
*The youngest runs just like the wind, speeding through the race.

"He is young in years, we let him run!" the other two brothers explained, "'because though he is surely number one, he is second, in a way." Why is it?

A cricket has 6 legs, a squirrel has 4 legs and a spider has 8 legs.

In a local zoo, it was found that the total number of legs is 612. Also, there are equal number of each of the above animals/insects.

Can you find out how many animals are there in the zoo?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.

How did the man in the booth know to give him two tickets without even looking at him?

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?