Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

How can a man go eight days without sleep?

People put me on the table and cut me but do not eat me. What am I?

Replace the question mark in the picture below.

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

What is the next number in this matchsticks series riddle?

There are three identical triplets sisters. Demi is the oldest of them all and she always speaks the truth. Diana is the next one who is a liar always. Drew, the youngest of them all speaks both truth and lies randomly.

On a rainy day, a family friend Victor visited them. Since there were starkly identical, he was not able to recognize them. Thus to clarify, he asked one question to each one of them.

He started with the one standing on the left and asked, 'Which sister is in the middle of you three?' She answered, 'That's Demi.'

Then, he asked the one standing in the middle, 'What is your name?' She answered, 'I am Drew.'

Finally, he asked the one standing on the right, 'Who is standing in the middle?' She answered, 'She is Diana.'

Victor was left baffled. He asked the questions three times and received different answers every time.

Can you tell who was who?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?