private void ButtonTwoBtn_Click(object sender, EventArgs e)
        {
            var _expFunASS = TextBoxEFA.SelectionStart;

            if (Checked._checkedTextBoxEFA == true)
            {
                TextBoxEFA.Focus();
                TextBoxEFA.Text = TextBoxEFA.Text.Insert(_expFunASS, "2");
                _expFunASS++;

                TextBoxEFA.SelectionStart = _expFunASS;
                _charChecker.IsCommaCheckerExpFunAMethod();
                _charChecker.IsMinusCheckerExpFunAMethod();
            }
            var _expFunXSS = TextBoxEFX.SelectionStart;

            if (Checked._checkedTextBoxEFX == true)
            {
                TextBoxEFX.Focus();
                TextBoxEFX.Text = TextBoxEFX.Text.Insert(_expFunXSS, "2");
                _expFunXSS++;

                TextBoxEFX.SelectionStart = _expFunXSS;
                _charChecker.IsCommaCheckerExpFunXMethod();
                _charChecker.IsMinusCheckerExpFunXMethod();
            }
        }
        private void ButtonTwoBtn_Click(object sender, EventArgs e)
        {
            var _expFunASS = TextBoxEFA.SelectionStart;

            // _valueStringEFA = TextBoxEFA.Text;
            //  _isComma = _valueStringEFA.Contains(Checked.)
            //_valueString = ValueToAbsTxb.Text;
            //_isComma = _valueString.Contains(CommaSymbol);
            if (Checked._checkedTextBoxEFA == true)
            {
                TextBoxEFA.Focus();
                TextBoxEFA.Text = TextBoxEFA.Text.Insert(_expFunASS, "2");
                _expFunASS++;
                //_a += Convert.ToDouble(TextBoxEFA.Text);
                TextBoxEFA.SelectionStart = _expFunASS;
                _charChecker.IsCommaCheckerExpFunAMethod();
                _charChecker.IsMinusCheckerExpFunAMethod();
                //_charChecker.IsCommaCheckerFunLinAMethod();
                // _charChecker.IsMinusCheckerFunLinAMethod();
                // _charChecker.IsMinusCheckerMethod();
            }
            var _expFunXSS = TextBoxEFX.SelectionStart;

            if (Checked._checkedTextBoxEFX == true)
            {
                TextBoxEFX.Focus();
                TextBoxEFX.Text = TextBoxEFX.Text.Insert(_expFunXSS, "2");
                _expFunXSS++;
                // _b += Convert.ToDouble(TextBoxLinFunB.Text);
                TextBoxEFX.SelectionStart = _expFunXSS;
                _charChecker.IsCommaCheckerExpFunXMethod();
                _charChecker.IsMinusCheckerExpFunXMethod();
                //  _charChecker.IsCommaCheckerFunLinBMethod();
                ///   _charChecker.IsMinusCheckerFunLinBMethod();
            }
        }