code: public static BigInteger exactDivide(BigInteger dividend, BigInteger divisor) {
      if (divisor.signum() == 0) {
        throw new ArithmeticException("BigInteger divide by zero");
      }
      return INSTANCE.get().exactDivImpl(dividend, divisor);
    }
docs: Divide dividend by divisor. This method only returns correct answers when the division produces
  no remainder. Correct answers should not be expected when the divison would result in a
  remainder.
  
  @return dividend / divisor
  @throws ArithmeticException if divisor is zero