How about org.apache.commons.math ? They have a Fraction class that takes a double.
http://commons.apache.org/math/api-1.2/org/apache/commons/math/fraction/Fraction.html
You should be able to extend it and give it functionality for the 64th. And you can also add a toString that will easily print out the whole number part of the fraction for you.
Fraction(double value, int
maxDenominator) Create a fraction
given the double value and maximum
denominator.
