Detecting an emulator's number representation

[EdS2]

Aside from the question of how many bits or bytes are used, an emulator can either use binary or decimal internally. I'm thinking the kinds of inaccuracies of the two systems will differ, so there might be some simple calculation which shows whether binary or decimal is in use.

For example, and where I first noticed this, 800/81 has a pleasing form on a decimal machine such as the 15C:
800 ENTER 81 /
9.876543210

Whereas a workalike emulator which uses (binary) floats internally returns
9.876543209

I see the same two results respectively on an HP35 microcode emulator and an HP35 workalike emulator.

However, I can imagine a mere difference in precision or in rounding tactics might also show this difference: with a few more digits we see the more precise result 9.87654320988 and indeed the mathematic result is a repeating fraction: 9.87654320987654320...

Any ideas for simple calculations which might expose the difference?