The species diversity of animals on earth is (in $;\%$)

According to Robert May,the global species diversity is about:

Animals account for more than $P$ of all species recorded. Even if we combine all plant species (algae,fungi,bryophytes,gymnosperms,and angiosperms),they account for no more than $Q$ of the total percentage.

How do scientists extrapolate the total number of species on Earth?

According to $IUCN$ $(2004)$,what is the total number of plant and animal species described so far?

Which one of the following has the highest number of species in nature?