If eleven plus two equals one, what does nine plus five equal?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Two brothers were watching a horror film on video late one night. One brother dozed off and dreamed that he was being chased by the crazy man from the movie, who was trying to kill him. In the dream, he hid in a cupboard. There was no sound except his heart pounding, and he had no idea where his crazed captor was. He was terrified! At that moment, the video finished, and his brother put his hand on the shoulder of his sleeping sibling to wake him. The shock at that tense moment was enough that the sleeping brother suffered a massive heart attack and died instantly. True or false?

A and B have a certain number of chocolates with them. If B gives one chocolate to A, they will have an equal number of chocolates. But if A gives one chocolate to B, then A will be left with half the number of chocolates that B has.

Can you find out the number of chocolates they have right now?

A dead body is found outside a multi-story multinational company. The case is reported and a homicide detective is called on the crime scene.

He looks at the body and then towards the building. From the position of the body, it is evident that the victim committed suicide. He goes to the first floor of the building and then walks in the direction of the dead body, opens the window and toss a coin in the air.

He goes to second floor and again repeats the process. He keeps doing this till he is done on all the floors. Then he returns back to the floor and tells his team that it is a murder.

How in heaven did he deduce that?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

Three brothers Jacob, John, and James live in Mexico City. The product of the ages of these brothers is 175. Jacob and John are twins. How old is James?

Name the three-letter word that can complete the below words:

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E