İki tam sayının kesirleri olarak ifade edilebilen sayılar, rasyonel sayılar olarak adlandırılır.
- Numbers that can be expressed as fractions of two whole numbers are called rational numbers.
With fresh material, taxonomic conclusions are leavened by recognition that the material examined reflects the site it occupied; a herbarium packet gives one only a small fraction of the data desirable for sound conclusions. Herbarium material does not, indeed, allow one to extrapolate safely: what you see is what you get.