Any probability greater than zero can be expressed as a fraction of one: p = 0.0005 = 1/2000, thus transforming leading zeros into trailing zeros, which may be significant figures depending on the case.
Note that, on the other hand, the inverse of physical quantity (other than time/frequency) is not generally an intrinsically meaningful number.
They convey information, but they are not significant figures, which is a term with a specific meaning.
Well, if you have to nitpick...
Any probability greater than zero can be expressed as a fraction of one: p = 0.0005 = 1/2000, thus transforming leading zeros into trailing zeros, which may be significant figures depending on the case.
Note that, on the other hand, the inverse of physical quantity (other than time/frequency) is not generally an intrinsically meaningful number.