静态构造的 C# 问题

有这么一堂课

public class Calculator
{
  private Calculator()
        {
            
        }

  public static Calculator WorkingWithConsole(string UserInput) 
        {
            var Calculator = new Calculator();
            string[] split = Regex.Split(UserInput, @"(\b[-+*\/]|[+-]?\d+[^-+*\/]\d+|[+-]?\d+|[- 
            +*\/()])").Where(x => !string.IsNullOrWhiteSpace(x)).ToArray(); 
            Checking(split);
            CalculatingFromConsole(split);
            return Calculator;
        }

public static Calculator WorkingWithFile(string FilePath)
        {
            var Calculator = new Calculator();
            if (!File.Exists(FilePath))
            {
                throw new FileNotFoundException("Файл не найден");
            }
            var oldPath = FilePath;
            var tmp = new[] { Path.GetDirectoryName(oldPath), "Result.txt" };
            _resultPath = Path.Combine(tmp);
            using (FileStream file = new FileStream(_resultPath, FileMode.Create)) {
                file.SetLength(0);
            }
            CalculatingFromFile(FilePath);
            return Calculator;
        }
private  void Checking(string[] line)
       {
         .....
       }
private  void CalculatingFromFile(string[] line)
       {
         .....
       }
}

其中有静态构造函数。

问题是方法

CalculatingFromConsole(split);
Checking(split);

不是静态的，因此 非静态字段错误需要对象引用

是否可以在不将它们转换为静态方法的情况下修复此错误？