> Early versions of Dart tried to use rational numbers by default, but then it was cancelled because denominator size can grow exponentially.

While I'm generally in favor of rational numbers as a default and believe that its "danger" is no different from that of big integers, there is some truth in this because Guido van Rossum of the Python fame has said the same thing [1]. It seems that you need some adjustments if you are already familiar to languages where rational numbers are not default.

[1] https://python-history.blogspot.com/2009/03/problem-with-int...