Editing Absolute convergence (section)

===Real and complex numbers===

When a series of real or complex numbers is absolutely convergent, any rearrangement or reordering of that series' terms will still converge to the same value. This fact is one reason absolutely convergent series are useful: showing a series is absolutely convergent allows terms to be paired or rearranged in convenient ways without changing the sum's value.

The [[Riemann rearrangement theorem]] shows that the converse is also true: every real or complex-valued series whose terms cannot be reordered to give a different value is absolutely convergent.