[42S] MANT Challenge

[Werner]

On the 41, you can use Synthetic Programming to come up with a short and efficient routine that returns the mantissa.
Not so on the 42S. Is anyone willing to give it a try?
A few borderline cases that may foil your first attempts (on a real 42S, not Free42):

0
1.00000000001e-01
-9.99999999999
9.99999999999e499

Good luck,
Werner