Can you fill the blank with the correct number?

6 30 870 756030 _____

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

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

Count the number of triangles in the given picture.

What number do you get when you multiply all of the numbers on a telephone's number pad?

Can you count the number of matches in the picture below ?

Readers with the most attentive eyes can find three differences between the pictures of a cat on a box. Test your observation power now!

Rob is taller than Edwin, and Jurgen is shorter than Rob.
Of only one of the following statements, we now certainly know it is correct:

A.Edwin is taller than Jurgen
B.Jurgen is taller than Edwin
C.It cannot be determined if Jurgen or Edwin is the tallest.

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?