方法一

//缩写金币
    public static string AcCoin(long gold) {
        string str = "";
        long k = (long)Mathf.Pow(10, 3);
        long m = (long)Mathf.Pow(10, 6);
        long b = (long)Mathf.Pow(10, 9);
        long t = (long)Mathf.Pow(10, 12);
        if (gold >= t)
            str = (gold / (double)t).ToString("0.0") + "t";
        else if (gold >= b)
            str = (gold / (double)b).ToString("0.0") + "b";
        else if (gold >= m)
            str = (gold / (double)m).ToString("0.0") + "m";
        else if (gold >= k)
            str = (gold / (double)k).ToString("0.0") + "k";
        else
            str = gold.ToString();
        return str;
    }

方法二

public static string GetSuffix(int num) {
    string suffix = "";
    string s = num.ToString();

    if (num < 10000) return num.ToString();

    switch ((s.Length - 1) / 3) {
        case 0:
            suffix = string.Empty;
            break;
        case 1:
            suffix = "K";
            break;
        case 2:
            suffix = "M";
            break;
        case 3:
            suffix = "B";
            break;
        case 4:
            suffix = "T";
            break;
        case 5:
            suffix = "Qa";
            break;
        case 6:
            suffix = "Qi";
            break;
        case 7:
            suffix = "S";
            break;
    }

    if (s.Length % 3 == 1)
        return s.Substring(0, 1) + "." + s.Substring(1, 1) + s.Substring(2, 1) + suffix; // 4.35m

    if (s.Length % 3 == 2)
        return s.Substring(0, 1) + s.Substring(1, 1) + "." + s.Substring(2, 1) + suffix; // 4.35m

    if (s.Length % 3 == 0)
        return s.Substring(0, 1) + s.Substring(1, 1) + s.Substring(2, 1) + suffix; // 4.35m

    return "";
}

总结
都是传递你希望变化的金币数量进入方法中，实在你想要的金币效果