You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

passagemath-lcalc
10.4.56

This version was deleted from PyPI around 2025-04-03. Installing fails with:
$ pip3 install passagemath-lcalc==10.4.56 ERROR: Could not find a version that satisfies the requirement passagemath-lcalc==10.4.56