Can you find the key in the picture below?

Name a key which is hardest to turn.

A bank customer had $100 in his account. He then made 6 withdrawals. He kept a record of these withdrawals, and the balance remaining in the account, as follows:

Withdrawals Balance left
$50 $50
$25 $25
$10 $15
$8 $7
$5 $2
$2 $0
----- -----
$100 $99

Why are the Totals not tallying?

Can you find out which options fits best with the missing column?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

What does this mean?

CCCCCCC

Find out the missing number in the picture attached:

Who has married many women but was never married?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

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?