As far "while" loops don't work, so i run the "while" loop in other code to print the tests.

There're no specific reason of number of tests (666).

relative error is now 10^-3 and rounding is not needed now.

I kind of have to clarify that the [...,...] meant range notation (inclusive on both ends).

or maybe in the [floor(ρ),ceil(ρ)] range?

hmm... would error tolerance of ±(1 kg/m^3) be wide enough, though...

will republishing (as another kata with other hexadecimal identifier, internal contents such as material names are changed) actually do an effect?

on progress making random tests