R version 3.4.4 (2018-03-15) -- "Someone to Lean On"
Copyright (C) 2018 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
[...]

> round(55.8/1.8)
[1] 31
> 55.8/1.8
[1] 31
> round(55.8/1.8) == (55.8/1.8)
[1] FALSE
> round(55.8/1.8) - (55.8/1.8)
[1] 3.552714e-15

> format(55.8/1.8, digits=22)
[1] "30.99999999999999644729"