HOWTO: Display a Number as a Fraction

ID: Q185479

The information in this article applies to:

Microsoft Visual Basic for Applications version 5.0

SUMMARY

This article provides three routines to convert a decimal fraction to the form "a b/c".

MORE INFORMATION

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In many instances, it is useful to be able to output a decimal value as a fraction in the form "a/b" or "a b/c". This article provides three routines that perform that function.


Function        Description
--------        -----------

Frac2Num        Returns a normalized fraction with the denominator in the
                range of 2..8.

Frac2NumA       Returns a non-normalized fraction with the denominator you
                specify.

Frac2NumB       Returns a normalized fraction based on a denominator you
                specify.

A normalized fraction contains the smallest possible denominator. The GCF() function (Greatest Common Factor) is used in the normalization process.

Example

Non-normalized : 4/6
Normalized : 2/3

Sample Code

Create a new project and add the following code to a Module:


      Function Num2Frac (ByVal X As Double) As String
      Dim Fixed As Double, Temp As String
        X = Abs(X)
        Fixed = Int(X)
        If Fixed > 0 Then
          Temp = CStr(Fixed)
        End If
        Select Case X - Fixed
          Case .1 To .145
            Temp = Temp + " 1/8"
          Case .145 To .182
            Temp = Temp + " 1/6"
          Case .182 To .225
            Temp = Temp + " 1/5"
          Case .225 To .29
            Temp = Temp + " 1/4"
          Case .29 To .35
            Temp = Temp + " 1/3"
          Case .35 To .3875
            Temp = Temp + " 3/8"
          Case .3875 To .45
            Temp = Temp + " 2/5"
          Case .45 To .55
            Temp = Temp + " 1/2"
          Case .55 To .6175
            Temp = Temp + " 3/5"
          Case .6175 To .64
            Temp = Temp + " 5/8"
          Case .64 To .7
            Temp = Temp + " 2/3"
          Case .7 To .775
            Temp = Temp + " 3/4"
          Case .775 To .8375
            Temp = Temp + " 4/5"
          Case .8735 To .91
            Temp = Temp + " 7/8"
          Case Is > .91
            Temp = CStr(Int(X) + 1)
        End Select
        Num2Frac = Temp
      End Function

      Function Num2FracA (ByVal X As Double, _
                          ByVal Denominator As Long) As String
      Dim Temp As String, Fixed As Double, Numerator As Long
        X = Abs(X)
        Fixed = Int(X)
        Numerator = Int((X - Fixed) * Denominator + .5) ' Rounding
        If Numerator = Denominator Then
          Fixed = Fixed + 1
          Numerator = 0
        End If
        If Fixed > 0 Then Temp = CStr(Fixed)
        If Numerator > 0 Then
          Temp = Trim$(Temp & " " & Numerator & "/" & Denominator)
        End If
        Num2FracA = Temp
      End Function

      Function Num2FracB (ByVal X As Double, _
                          ByVal Denominator As Long) As String
      Dim Temp As String, Fixed As Double, Numerator As Long
      Dim Factor As Long
        X = Abs(X)
        Fixed = Int(X)
        Numerator = Int((X - Fixed) * Denominator + .5)  ' Rounding
        If Numerator = Denominator Then
          Fixed = Fixed + 1
          Numerator = 0
        End If
        If Fixed > 0 Then
          Temp = CStr(Fixed)
        End If
        If Numerator > 0 Then
          Factor = GCF(Numerator, Denominator)  ' Factor for normalization.
          Temp = Trim$(Temp & " " & Numerator / Factor & "/" & _
                       Denominator / Factor)
        End If
        Num2FracB = Temp
      End Function

      Function GCF (ByVal X As Long, ByVal Y As Long) As Long
      '
      ' Returns the Greatest Common Factor.
      ' The largest number that will evenly divide into both X and Y.
      '
      Dim Temp As Long
        X = Abs(X)        ' Make both numbers positive.
        Y = Abs(Y)
        Temp = X Mod Y
        Do While Temp > 0
          X = Y
          Y = Temp
          Temp = X Mod Y
        Loop
        GCF = Y
      End Function

Run the project and then press CTRL+BREAK to pause.

In the Debug/Immediate window, type the following:
?Num2Frac(3.54), Num2FracA(3.54,8), Num2FracB(3.54,8)
Results:
3 1/2
3 4/8
3 1/2

REFERENCES

For more information about getting help with Visual Basic for Applications, please see the following article in the Microsoft Knowledge Base:

Q163435 VBA: Programming Resources for Visual Basic for Applications

Additional query words: vba kbVBA kbVBp kbdta

Keywords : kbcode
Version : WINDOWS:5.0
Platform : WINDOWS
Issue type : kbhowto kbinfo