Fraction class, can turn any ordinary fraction into decimal

Fraction.cs

public class Fraction
{
    private int[] _decimalDigits;
    private int _cycleStart;

    private static int GCD(int a, int b)
    {
        if (a % b == 0)
        {
            return b;
        }

        bool aIsEven = (a & 1) == 0;
        bool bIsEven = (b & 1) == 0;

        if (aIsEven && bIsEven)
        {
            return 2 * GCD(a >> 1, b >> 1);
        } else if (aIsEven) {
            return GCD(a >> 1, b);
        } else if (bIsEven) {
            return GCD(a, b >> 1);
        } else if (a > b) {
            return GCD((a - b) >> 1, b);
        } else {
            return GCD((b - a) >> 1, a);
        }
    }

    public int IntegerPart { get; private set; }
    public int Numerator { get; private set; }
    public int Denominator { get; private set; }
    public int CycleLength
    {
        get
        {
            return _decimalDigits.Length - _cycleStart;
        }
    }

    public Fraction(int numerator, int denominator)
    {
        int gcd = GCD(denominator, numerator);

        IntegerPart = numerator / denominator;
        Numerator = (numerator - (denominator * IntegerPart)) / gcd;
        Denominator = denominator / gcd;
        ComputeDecimalForm();
    }

    private void ComputeDecimalForm()
    {
        HashSet<int> numerators = new HashSet<int>();
        List<int> decimalDigits = new List<int>();
        int numerator = Numerator;
        int denominator = Denominator;
        int countOfZeroes = 0;

        while (numerator < denominator && numerator > 0)
        {
            numerator *= 10;
            countOfZeroes++;
        }
        
        while (numerator % denominator != 0)
        {
            while (numerator < denominator)
            {
                numerator *= 10;
            }

            if (!numerators.Add(numerator))
            {
                int cycleStart = 0;

                foreach (var item in numerators)
                {
                    if (numerator == item)
                    {
                        break;
                    }
                    cycleStart++;
                }

                _cycleStart = cycleStart + countOfZeroes;
                _decimalDigits = new int[countOfZeroes + decimalDigits.Count];
                Array.Copy(decimalDigits.ToArray(), 0, _decimalDigits, countOfZeroes, decimalDigits.Count);
                return;
            }

            decimalDigits.Add(numerator / denominator);
            numerator = numerator % denominator;
        }
        decimalDigits.Add(numerator / denominator);

        _decimalDigits = new int[countOfZeroes + decimalDigits.Count];
        Array.Copy(decimalDigits.ToArray(), 0, _decimalDigits, countOfZeroes, decimalDigits.Count);
        _cycleStart = _decimalDigits.Length;
    }

    public override string ToString()
    {
        var sb = new System.Text.StringBuilder(_decimalDigits.Length + 4);
        sb.AppendFormat("{0}.", IntegerPart);

        for (int i = 1; i < _cycleStart; i++)
        {
            sb.Append(_decimalDigits[i]);
        }

        if (_cycleStart < _decimalDigits.Length)
        {
            sb.Append("(");
            for (int i = _cycleStart; i < _decimalDigits.Length; i++)
            {
                sb.Append(_decimalDigits[i]);
            }
            sb.Append(")");
        }

        return String.Format("{0}/{1} == {2}", Numerator + IntegerPart * Denominator, Denominator, sb);
    }
}