A really innovative way to store exact floating point numbers:

1. for "safe numbers" (numbers whose value can be expressed precisely in floating point), store them as is
2. for non-"safe numbers", store two safe numbers as denominator and nominator.

There is a lot of this method comparing to the other alternatives:

• BigDecimal: a lot faster than arbitrary precision BigDecimal
• Rational: denom and nom deoesn't blow up to extremely large numbers

And it is also faster and uses less space.