What is the next number in this matchsticks series riddle?

What is next number in the pattern below:

131 517 192 123 ?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

I am written with two letters.
I said with the one.
I usually am seen with the two.

Who am I?

During an interview, the interviewer ordered hot coffee for the candidate to relieve the stress. The coffee was kept before him. After a minute, the interviewer asked him, 'What is before you?' He replied 'Tea'.

The candidate was selected immediately. Why?

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?

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

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

Below, you can see three complete equations and one incomplete. Based on the three complete ones, can you complete the incomplete one?

5 $ 4 $ 3 $ 9 = 4215
6 $ 9 $ 2 $ 6 = 3816
4 $ 7 $ 3 $ 3 = 1122
7 $ 2 $ 7 $ 4 = ____