CalculateHistory.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp20
{
    internal class CalculateHistory
    {
        public int index { get; set; }
        public string FirstOperand { get; set; }
        public string SecondOperand { get; set; }
        public string opertaor { get; set; }
        public string Result { get; set; }

        public string GetHistory()
        {
            return $"Calculate({index}). {FirstOperand} {opertaor} {SecondOperand} = {Result}";
        }

        public CalculateHistory(int index,string FirstOperand,string Operator,string SecondOperand,string Result)
        {
            this.index = index;
            this.FirstOperand = FirstOperand;
            this.SecondOperand = SecondOperand;
            this.opertaor = Operator;
            this.Result = Result;
        }
    }
}