Fun fact - in Polish we have separate forms for 1 (singular), 2-4 (plural but nit many) and everything else. Zero is in “everything else” 0 książek 0.5 książki 1 książka 2,3,4 książki 2.5 książki 5 and above książek 5.5 (any other fraction) książki >100 and a fraction - depends Singular is for one. The first plural is for things kind of treated as individual objects. The second plural is for things that are treated a…
4 books were sitting on the shelf = Stały 5 książek na półce [feminine plural verb, which makes sense]
5 books were sitting on the shelf = Stało 5 książek na półce [neuter singular???]
As someone learning Polish this is quite confusing.