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?

Find the value of "?" in the ball picture Riddle below:

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Complete the table series riddle by finding the number that can replace "??".

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

I’m tall when I’m young, and I’m short when I’m old. What am I?

In the picture given below, can you find out which digit will take place of the question mark?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?

In the image below, can you find the value of an angle(y)

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?