Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

A Shopkeeper sold a few chickens to four different customers on a particular day. It was such that each customer purchased half of the remaining chickens and half the chicken more.

Can you find out how many chicken were sold by the shopkeeper on that day if we tell you that the fourth customer bought a single chicken ?

How many sides does a circle have?

In the given picture, you can find two letters missing. When two particular letters are placed in the missing spots, you get an eight-letter word while reading in the anti-clockwise direction. Can you find out the missing letters and the missing word eventually?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.
How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly

I make two people out of one. What am I?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?