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

Name a key which is hardest to turn.

I have two coins.
* One of the coins is a faulty coin having a tail on both sides of it.
* The other coin is a perfect coin (heads on side and tail on other).

I blindfold myself and pick a coin and put the coin on the table. The face of the coin towards the sky is the tail.

What is the probability that another side is also tail?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

My grandson is about as many days as my son in weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 120 years. Can you tell me my age in years ?

Can you find the thief by just looking at the picture below?

Next Number in the Series,

5, 16, 49, 104, ?

Can you fill the blank with the correct number?

6 30 870 756030 _____