Editing P-adic number (section)

== Cardinality ==
Both <math>\Z_p</math> and <math>\Q_p</math> are [[uncountable set|uncountable]] and have the [[cardinality of the continuum]].<ref>{{Harv|Robert|2000|loc=Chapter 1 Section 1.1}}</ref> For <math>\Z_p,</math> this results from the {{mvar|p}}-adic representation, which defines a [[bijection]] of <math>\Z_p</math> on the [[power set]] <math>\{0,\ldots,p-1\}^\N.</math> For <math>\Q_p</math> this results from its expression as a [[countably infinite]] [[union (set theory)|union]] of copies of <math>\Z_p</math>:
<math display="block">\Q_p=\bigcup_{i=0}^\infty \frac 1{p^i}\Z_p.</math>