In the spirit of using existing, tested and stable libraries of code, I started using the Apache-Commons-Math library and its BigFraction class to perform some rational calculations for an Android app I'm writing called RationalCalc. It works great for every task that I have thrown at it, except for one nagging problem. When dividing certain BigFraction values, I am getting incorrect results. If I create a BigFraction with the inverse of the divisor and multiply instead, I get the same incorrect answer but perhaps that is what the library is doing internally anyway. Does anyone know what I am doing wrong? The division works correctly with a BigFraction of 2.5 but not 2.51, 2.49, etc... // *** incorrect! *** BigFraction one = new BigFraction(1.524); //one: 1715871458028159 / 1125899906842624 BigFraction two = new BigFraction(2.51); //two: 1413004383087493 / 562949953421312 BigFraction three = one.divide(two); //three: 0 Log.i("solve", three.toString()); //should be 0.607171315 ?? //returns 0 // *** correct! **** BigFraction four = new BigFraction(1.524); //four: 1715871458028159 / 1125899906842624 BigFraction five = new BigFraction(2.5); //five: 5 / 2 BigFraction six = four.divide(five); //six: 1715871458028159 / 2814749767106560 Log.i("solve", six.toString()); //should be 0.6096 ?? //returns 0.6096