Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

A doctor and a boy were fishing. The boy was the doctor’s son, but the doctor was not the boy’s father. Who was the doctor?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

What is the next number in this series?

4,12,84,3612....

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Can you write down eight eights so that they add up to one thousand?

Find the number of squares in the below picture

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Consider all the numbers between 1 and 1 million. Among all these numbers, there is something very special about the number 8 and the number 2202. What is it?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?