static final int MAX_EXPONENT = 100;

  /*
   * Duplicated from LongMath.
   * binomial(biggestBinomials[k], k) fits in a long, but not
   * binomial(biggestBinomials[k] + 1, k).
   */
  static final int[] biggestBinomials = {
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    3810779,
    121977,
    16175,
    4337,
    1733,
    887,

  static final int MAX_EXPONENT = 100;

  /*
   * Duplicated from LongMath.
   * binomial(biggestBinomials[k], k) fits in a long, but not
   * binomial(biggestBinomials[k] + 1, k).
   */
  static final int[] biggestBinomials = {
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    3810779,
    121977,
    16175,
    4337,
    1733,
    887,

        }
      } while (!Impl.GUAVA.noMulOverflow(longsToMul[i][0], longsToMul[i][1]));

      int k = binomials[i][1] = RANDOM_SOURCE.nextInt(MathBenchmarking.biggestBinomials.length);
      binomials[i][0] = RANDOM_SOURCE.nextInt(MathBenchmarking.biggestBinomials[k] - k) + k;
    }
  }

  @Benchmark
  long factorialDouble(int reps) {
    long tmp = 0;
    for (int i = 0; i < reps; i++) {

  public void testConstantsBiggestBinomials() {
    for (int k = 0; k < LongMath.biggestBinomials.length; k++) {
      assertTrue(fitsInLong(BigIntegerMath.binomial(LongMath.biggestBinomials[k], k)));
      assertTrue(
          LongMath.biggestBinomials[k] == Integer.MAX_VALUE
              || !fitsInLong(BigIntegerMath.binomial(LongMath.biggestBinomials[k] + 1, k)));

  }

  public void testConstantsBiggestBinomials() {
    for (int k = 0; k < IntMath.biggestBinomials.length; k++) {
      assertTrue(fitsInInt(BigIntegerMath.binomial(IntMath.biggestBinomials[k], k)));
      assertTrue(
          IntMath.biggestBinomials[k] == Integer.MAX_VALUE
              || !fitsInInt(BigIntegerMath.binomial(IntMath.biggestBinomials[k] + 1, k)));

    // so denominator must be a divisor of numerator.
    return x * (numerator / denominator);
  }

  /*
   * binomial(biggestBinomials[k], k) fits in a long, but not binomial(biggestBinomials[k] + 1, k).
   */
  static final int[] biggestBinomials = {
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    Integer.MAX_VALUE,
    3810779,
    121977,
    16175,
    4337,
    1733,

    checkNonNegative("n", n);
    checkNonNegative("k", k);
    checkArgument(k <= n, "k (%s) > n (%s)", k, n);
    if (k > (n >> 1)) {
      k = n - k;
    }
    if (k < LongMath.biggestBinomials.length && n <= LongMath.biggestBinomials[k]) {
      return BigInteger.valueOf(LongMath.binomial(n, k));
    }

    BigInteger accum = BigInteger.ONE;

    long numeratorAccum = n;
    long denominatorAccum = 1;