Some commentary to add to the pages for your cases

[TediusTimmy]

Mike Cowlishaw - The REXX programming language was originally written by Mike Cowlishaw (https://www.rexxla.org/rexxlang/history/index.srsp). The Java BigDecimal class is based on the specification for the REXX programming language (https://docs.oracle.com/javase/8/docs/api/java/math/BigDecimal.html : look up the ANSI specification number). Mike Cowlishaw also wrote the "General Decimal Arithmetic Specification" which is used by Python's decimal module (https://docs.python.org/3/library/decimal.html). He also was the reason there are now decimal types in IEEE-754.

bc and dc - these tools generally use the same numerics, given that bc was originally written as a compiler for dc. And they do math in decimal (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html): specifically their numeric type is a scaled arbitrary-precision integer. The most notable thing about these two is that bc is on every Android phone (as Android is based on Linux, which follows POSIX, in which bc is a required tool).