The set of whole numbers is the set of natural numbers along with zero. so W = the set of whole numbers = 0,1,2,3,............ (no fractions or decimals!)
so Zero is the least number of the set of Whole numbers.
As the whole numbers is an infinite set we can't determine the highest number of this set.
The set of Whole numbers is a subset of Rational numbers
source: http://www.mathsisfun.com/whole-numbers.html (for the no fractions part)
http://www.tutorvista.com/search/what-are-the-characteristics-of-whole-numbers (for the rest)
shamemi: for the no decimals part and double checking part
suen: for the typing part and searching for information part
team members: Su En and Shamemi~!