For example, when one is talking about a chemistry equation and they use values one wouldn't see in real life to illustrate a point better, or give a specific example that requires extra steps that likely won't be required in the usual cases, what would they include to say
this is an example that wouldn't(or less likely to) exist in real life, but it is picked as it illustrates the point better ?
A general idiom/phrase for
unarbitrary as in
the example was picked with care, it isn't arbitrary would work as well.
Thanks in advance.