2nd list all natrual numbers?

Question

{-6,,-4/5,,0,,0.8,,square root of 5,,pie,,square root of 25}

Answer 1

0 and 5
Sometimes 0 is not considered a natural number and somtimes its is.
Natural numbers do not include negative numbers, fractions, irrational or imaginary numbers

Answer 2

Some systems include 0, others don't, so for that look in your textbook. After that its ever positive integer, so the answer is 0 and 5 or just 5.

Answer 3

http://en.wikipedia.org/wiki/Natural_numbers