It's surprising that none of the popular high level languages that borrow so much else from Lisp haven't borrowed its rational number type. Really the whole numeric tower makes a ton of sense, and you can always declare floats if needed.
Thanks for the encouragement to look up lisp's numeric tower (https://en.wikipedia.org/wiki/Numerical_tower), that was interesting to compare to the languages I'm more familiar with.
Rationals are not really great for a long series of calculations. E.g. imagine taking the average of a bunch of numbers like 1.15542345089. It will blow up your CPU usage to stratospheric levels.
Including Lisp. Not every Lisp dialect has rationals.