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

What goes up but never comes down?

Which digit occurred maximum times between the number 1 and 1000?

A red house is made out of red bricks. A yellow house is made out of yellow bricks. And, a blue house is made out of blue bricks. So, what is a greenhouse made of?

What has many teeth, but cannot bite?

Keyboard words are not in alphabetical order, Why?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Katniss and Peeta are liars. They both lie on some specific days.

Katniss lies on Fridays, Saturdays and Sundays. She speaks the truth on all other days.

Peeta lies on Tuesdays, Wednesdays and Thursdays. He speaks the truth on all other days.

Can you tell that one day of the week when both of them will say "Tomorrow, I will lie."?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

What can go through glass without breaking it?