string[] unitSymbol = new string[] { "", "만", "억", "조", "경", "해" };

public string CorvertNumString( long value , int cnt = 2)
    {
        if ( cnt == 0 )
            return "Cnt input ERROR";

        int n = 0;
        StringBuilder sb = new StringBuilder();

        for ( long t = value; t != 0; t /= 10000 )
            n++;

        sb.Insert( 0, value / (long)Mathf.Max(1, Mathf.Pow( 10000 , n - cnt )));

        for ( int i = 0; i < cnt && i < n - 1; i++ )
            sb.Insert( sb.Length-( Mathf.Min( n , cnt) -i -1 )*4, unitSymbol[ n - i - 1] );

        return sb.ToString();
     }

하루동안 월급돚거 하며 깎았는데 더 좋은 방법이 확 떠오르지 않네