I cannot get VBA in Excel to make the Userform Calculator i created to perform operations on numbers with decimals right

The decimal is being added correctly to the text in txtDisplay, but the calculation logic in the rest of the code is almost certainly converting the text to a numeric type that does not preserve decimals (for example, Integer, Long, or using integer division), or formatting the result with zero decimal places.

To make the calculator work with decimals, ensure all of the following in the calculation code (not just the decimal button):

1. Use a data type that supports decimals
   • Declare variables that hold numbers as Double (or as Variant and assign decimal values) instead of Integer or Long.
   • Example:

          Dim firstNumber As Double
          Dim secondNumber As Double
          Dim result As Double
     

2. Use normal division, not integer division
   • Use / for division, not \.
   • \ performs integer division and discards the decimal part.
   • Example:

          result = firstNumber / secondNumber   ' keeps decimals
          ' avoid: result = firstNumber \ secondNumber
     

3. Convert the textbox text to a decimal-capable type
   • When reading from txtDisplay.Text, convert to Double (or CDec into a Variant with Decimal subtype):

          firstNumber = CDbl(txtDisplay.Text)
          ' or
          firstNumber = CDec(txtDisplay.Text)
     

4. Do not format the result to zero decimal places
   • If using Format or FormatNumber, make sure the format allows decimals, for example:

          txtDisplay.Text = Format(result, "0.############")
          ' or simply
          txtDisplay.Text = CStr(result)
     

5. Ensure Excel’s decimal separator matches the input
   • If the system uses a comma as decimal separator but the calculator uses a dot (.), either:
     • Set Excel to use . as decimal separator, or
     • Replace . with the system separator before conversion.
   • In VBA, the decimal separator used by Excel can be controlled via Application.DecimalSeparator and Application.UseSystemSeparators:

          Application.DecimalSeparator = "."
          Application.UseSystemSeparators = False
     

     This forces Excel to treat . as the decimal separator.

The cmbdecimal_Click code itself is fine for inserting a single decimal point. The missing decimals in the result come from how the numbers are stored, converted, divided, or formatted elsewhere in the calculator code.

References:

• Application.DecimalSeparator property (Excel)
• Decimal data type