When can we add 2 to 11 and get 1 as the correct answer?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

If six children and two dogs were under an umbrella, how come none of them got wet?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

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?

What demands an answer, but asks no questions

Who has married many women but was never married?

Do You See It?