How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

It was a dark stormy night and a couple were in a car driving madly to a city. The car broke down and the husband had to go get help from someone who spoke his language. He was afraid to leave his wife alone in the car so he locked the car before leaving. When he came back, the car was in the same state as he had left it but his wife was dead, there was blood on the floor and there was a stranger in the car. What happened?

Solve the puzzle by telling what does below picture means.

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

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?