How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

10+10 and 11+11 can give you the same answer.

Explain how?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

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?

Forwards I am heavy, backward I am not. What am I?

Name a key which is hardest to turn.

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

Sherlock breaks into a crime scene. The victim is the owner who is slumped dead on a chair and have a bullet hole in his head. A gun lies on the floor and a cassette recorder is found on the table. On pressing the play button, Sherlock hears the message 'I have committed sins in my life and now I offer my soul to the great Lord' and followed a gunshot Sherlock smiles and informed the police that's its a murder.

Why did he think so?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?