What always comes into a house through the keyhole?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

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

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

Replace The Question Mark Below With the Correct Number.

2 {38} 3
4 {1524} 5
6 {3548} 7
8 {????} 9

Using Only Five 5's and any mathematical operator make sum as 37

Andrew sees a very rare bird named "Ruppell's vulture". Soon Andrew was dead. Can you explain the mystery, Mr. Sherlock?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

What is always in front of you but can’t be seen?

Before Mount Everest was discovered, what was the highest mountain in the world?