Upload Simulator 2 prestige point calculator

UploadSimulatorvalueModel.cs

public class UploadSimulatorvalueModel(decimal? rawExponent = null)
{
    public string Layer1 { get => this[1]; set => this[1] = value; }
    public string Layer2 { get => this[2]; set => this[2] = value; }
    public string Layer3 { get => this[3]; set => this[3] = value; }
    public string Layer4 { get => this[4]; set => this[4] = value; }

    public string this[int prestigeLayer]
    {
        get
        {
            var exponent = RawToPrestigeLayer(rawExponent, prestigeLayer);
            return Format(exponent);
        }
        set
        {
            var exponent = Parse(value);
            rawExponent = RawFromPrestigeLayer(exponent, prestigeLayer);
        }
    }

    private const string alphabet = "abcdefghijklmnopqrstuvwxyz";
    private static int SuffixToExponent(ReadOnlySpan<char> suffix)
    {
        return suffix switch
        {
            "" => 0,
            "k" => 3,
            "m" => 6,
            "b" => 9,
            "t" => 12,
            _ => 15 +
                alphabet.IndexOf(suffix[0]) * 3 * alphabet.Length
                + alphabet.IndexOf(suffix[1]) * 3
        };
    }
    private static string ExponentToSuffix(int exponent)
    {
        if (exponent == 0) return string.Empty;
        if (exponent % 3 != 0) throw new ArgumentException("Exponent must be a multiple of 3.");
        switch (exponent)
        {
            case 3: return "k";
            case 6: return "m";
            case 9: return "b";
            case 12: return "t";
        }
        exponent -= 15;
        int firstLetterIndex = exponent / (3 * alphabet.Length);
        int secondLetterIndex = (exponent / 3) % alphabet.Length;
        return string.Format("{0}{1}", alphabet[firstLetterIndex], alphabet[secondLetterIndex]);
    }
    private static string Format(decimal? exponent)
    {
        if (exponent is null) return "0";
        var remainder = exponent % 3;
        var suffixableExponent = (int)(exponent - remainder);
        var suffix = ExponentToSuffix(suffixableExponent);
        var mantissa = Math.Pow(10, (float)remainder);
        return $"{mantissa:F3}{suffix}";
    }
    private static decimal? Parse(ReadOnlySpan<char> number)
    {
        if(number is "0") return null;
        var suffixIndex = number.IndexOfAnyInRange('a', 'z');
        var suffix = number[suffixIndex..];
        var mantissa = number[..suffixIndex];
        var exponent = SuffixToExponent(suffix);
        return (decimal)Math.Log10(float.Parse(mantissa)) + exponent;
    }
    private static decimal? RawToPrestigeLayer(decimal? exponent, decimal prestigeLayer)
    {
        if (exponent is null) return null;
        ArgumentOutOfRangeException.ThrowIfGreaterThan(prestigeLayer, 4);
        ArgumentOutOfRangeException.ThrowIfLessThan(prestigeLayer, 1);
        for (int i = 1; i < prestigeLayer; i++)
        {
            exponent -= 50;
            exponent /= 2;
            if (exponent < 0) return null;
        }
        return exponent;
    }
    private static decimal? RawFromPrestigeLayer(decimal? exponent, decimal prestigeLayer)
    {
        if (exponent is null) return null;
        ArgumentOutOfRangeException.ThrowIfGreaterThan(prestigeLayer, 4);
        ArgumentOutOfRangeException.ThrowIfLessThan(prestigeLayer, 1);
        for (int i = 1; i < prestigeLayer; i++)
        {
            exponent *= 2;
            exponent += 50;
        }
        return exponent;
    }
}