Full Idea
The set of 'integers' is all of the negative natural numbers, and zero, together with the positive natural numbers.
Gist of Idea
The 'integers' are the positive and negative natural numbers, plus zero
Source
Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5)
Book Reference
Friend,Michèle: 'Introducing the Philosophy of Mathematics' [Acumen 2007], p.16
A Reaction
Zero always looks like a misfit at this party. Credit and debit explain positive and negative nicely, but what is the difference between having no money, and money being irrelevant? I can be 'broke', but can the North Pole be broke?