If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

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?

I know a nine-letter word having only one vowel.
Do you ?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

If a wheel has 54 spokes, how many spaces are there between the spokes?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

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

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?