<div id="comment:0"></div> We deprecate `is_RealNumber`, `is_ComplexNumber`, `is_AlgebraicNumber`, `is_RealIntervalFieldElement`, ... `git grep 'is_.*Number('` and `git grep -E 'is_(Real|Complex).*Element[(]'` only shows a small number of uses. We replace all uses either by - `isinstance` tests with the element class (if the module providing it is imported already) or - `isinstance` tests of the parent with an abc defined in `sage.rings.abc` See also: - #24457 - discussion in [this sage-devel thread](https://groups.google.com/forum/#!topic/sage-devel/wEzb0awmyN0) Depends on #32566 CC: @tscrim Component: **basic arithmetic** _Issue created by migration from https://trac.sagemath.org/ticket/24525_