private string GetExpression(List <OperationBase> checkedOperations, int numbers) { string exp = string.Empty; int[] arr = new int[numbers]; for (int i = 0; i < numbers; i++) { OperationBase operation = GetOperation(checkedOperations, checkedOperations.Count); if (i == 0) { arr[i] = operation.GenerateFirstNumber(); exp += arr[i]; continue; } int start = arr[i - 1]; int value = operation.GenerateNextNumber(start); exp += (operation.Operator + value); arr[i] = Convert.ToInt32(new DataTable().Compute(exp.Replace('x', '*'), null)); if (i == numbers - 1) { exp += "="; } } return(exp); }