code: public String toFString(int digits) {
          if (b.compareTo(BigInteger.ONE) != 0) {
              MathContext mc = new MathContext(digits, RoundingMode.DOWN);
              BigDecimal f = (new BigDecimal(a)).divide(new BigDecimal(b), mc);
              return (f.toString());
          } else {
              return a.toString();
          }
      }
docs: Return a string in floating point format.
  
  @param digits The precision (number of digits)
  @return The human-readable version in base 10.