C#

private void CalculateTheMortgage()
      {
          //  (Loan Value) *  (1 + r/12) ^ p =  (12x / r)  *  ((1 + r/12)^p - 1)
          // payment = (((Loan Value) *  (1 + r/12) ^ p) * r)/ (12 * ((1 + r/12)^p - 1)));
          double loanAmount = (double)txtLoanAmount.CurrentValue;  // price of total mortgage before down payment
          double taxesPerYear = (double)txtPropertyTax.CurrentValue; // this will divided by 12 and added to the monthly payment
          double downPayment = (double)txtDownPayment.CurrentValue; // down payment will be subtracted from the loan
          double interestRate = (double)udInterest.Value / 100;  // calculate interest from 100%
          double termOfLoan = (double)(udTerm.Value * 12); // monthly term
          double propertyTax = (double)txtPropertyTax.CurrentValue;
          double insurance = (double)txtInsurance.CurrentValue;

         double payment =  (loanAmount - downPayment) * (Math.Pow((1 + interestRate/12), termOfLoan) * interestRate)/(12 * (Math.Pow((1+interestRate/12), termOfLoan) - 1));

         // add on a monthly property tax
         payment = payment + (propertyTax + insurance) / 12;

         txtPayment.CurrentValue = (int)payment;
      }

private void CalculateTheMortgage()
      {
          //  (Loan Value) *  (1 + r/12) ^ p =  (12x / r)  *  ((1 + r/12)^p - 1)
          // payment = (((Loan Value) *  (1 + r/12) ^ p) * r)/ (12 * ((1 + r/12)^p - 1)));
          double loanAmount = Convert.ToDouble(txtLoanAmount.Text);// price of total mortgage before down payment
          double taxesPerYear = Convert.ToDouble(txtPropertyTax.Text); // this will divided by 12 and added to the monthly payment
          double downPayment = Convert.ToDouble(txtDownPayment.Text); // down payment will be subtracted from the loan
          double interestRate = (double)udInterest.Value / 100;  // calculate interest from 100%
          double termOfLoan = (double)(udTerm.Value * 12); // monthly term
          double propertyTax = Convert.ToDouble(txtPropertyTax.Text);
          double insurance = Convert.ToDouble(txtInsurance.Text);


          double payment = (loanAmount - downPayment) * (Math.Pow((1 + interestRate / 12), termOfLoan) * interestRate) / (12 * (Math.Pow((1 + interestRate / 12), termOfLoan) - 1));

          // add on a monthly property tax
          payment = payment + (propertyTax + insurance) / 12;


          txtPayment.CurrentValue = (int)payment;
      }

txtPayment.CurrentValue = (int)payment;

'System.Windows.Forms.TextBox' does not contain a definition for 'CurrentValue' and no extension method 'CurrentValue' accepting a first argument of type 'System.Windows.Forms.TextBox' could be found (are you missing a using directive or an assembly reference?)

BrowsePatientForm.MdiParent = this;

BrowsePatientForm.MdiParent = frmMain;