13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Why is the Hole below a Lock?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

What Time Should the last watch show in the below figure?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

How many times can you subtract the number 5 from 25?

Why Aeroplane windows are round?

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?