I'm writing a text for people without much scientific knowledge and at some places, it would be nice to wite things like: 1 mm = 0.001 m. You can probably understand, that I don't want to always manually write all thoese zeros, imagine picogram...
Is it possible - perhaps with siunitx - to write something like \SI{13}{\pico\gram} = \SI{13e-12}{\gram}, but getting as result 0.000 000 000 013 g instead of 13 x 10^(-12) g?