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

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

John was visiting his friend Jacob. He found out that his friend's wife had just killed a burglar in self-defense.
John asks Jacob about what happened and he told that "His wife was watching television when suddenly the bell rang. She thought that it is her husband Jacob but she found the burglar who attacked her instantly and she got so frightened that she killed the burglar immediately with the knife.
John asked the police to arrest his friend's wife. Why?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

A person was killed at a house party. When the police arrive, there are six people present in the house who are the friends of the victim. The name of the friends is Rohit, Aman, Nick, Gagan, and Randy.

Near the dead body, they find a few numbers written with blood by the victim on the floor. The numbers are 8, 5, 4, and 11.

The police arrests one of the friends for the murder. Whom did they arrest and why?

Steffi's daughter Jazelle needs to be picked up from school every day.
Steffi asks one of her colleagues to pick up Jazelle from the school. Steffi devised a password system to confirm that Jazelle goes with the correct colleague only.

The password on Monday was SJM16.
The password on Wednesday was TAW39.

What will the password be for Friday?

What does below chemistry rebus means?