intros n H'.
rewrite <- (Zabs_eq (Zpos (vNum b))); auto with zarith.
apply digit_anti_monotone_lt with (n := radix); auto.
rewrite digitVNumiSPrecision; auto with arith.
Qed.

Theorem pGivesDigit :
forall p : float, Fbounded b p -> Fdigit radix p <= precision.