Change time format from number like 600 to 06:00:00 - excel

Question

I have two workbooks, A and B, and two sheets, 1 and 2, in both the workbooks.I need to compare and find the match based on time.In workbook B in sheet 1 I have hh:mm:ss 24 hrs time format.But in workbook A I have the time from and to in number format like 600 and 800 etc. I have changed the time format in workbook 1 to hh:mm:ss but the problem I am getting after running for the first time is that the time has changed to 06:00:00 and again in the second run it is changed to 00:00:00.
Dim rCell As Range
Dim iHours As Integer
Dim iMins As Integer
Dim lrow As Long
Dim rn As Range
lrow = Sot.Range("d" & Rows.Count).End(xlUp).Row
Sot.Activate
Set rCell = Sot.Range(Cells(5, 4), Cells(lrow, 5))
For Each rn In rCell
If IsNumeric(rn.Value) And Len(rn.Value) > 0 Then
iHours = rn.Value \ 100
iMins = rn.Value Mod 100
rn.Value = (iHours + iMins / 60) / 24
rn.NumberFormat = "h:mm:ss"
End If
Next
For i = 5 To eRowplan
Time_from = Sotplan.Range("D" & i).Value
Time_To = Sotplan.Range("E" & i).Value
Time_from = TimeSerial(Hour(Time_from), Minute(Time_from),
Second(Time_from))
Time_To = TimeSerial(Hour(Time_To), Minute(Time_To), Second(Time_To))
If B_Time > "24:00" Then B_Time = "23:59"
B_Time = TimeSerial(Hour(B_Time), Minute(B_Time), Second(B_Time))
I tried with above codes

Answer 1

You can do it with the following if you want a VBA solution for e.g. 600 = 600 minutes
Dim c
For Each c In Selection
c.Value2 = c / (24 * 60)
c.NumberFormat = "hh:mm"
Next c
Or just use = A1 / (24 * 60) and format as Time
Update after comments
For 600 = 06:00:00 you can use the following
Dim c, tmpTime As Variant
For Each c In Selection
' Test if number
If IsNumeric(c.Value2) Then
' Split into character array, the Len(c.Value2) limits the size of the array otherwise
' an additional empty element is created
tmpTime = Split(StrConv(c.Value2, vbUnicode), Chr$(0), Len(c.Value2))
' Write results back and format
With c.Offset(0, 1)
.Value2 = Join(tmpTime, ":")
.NumberFormat = "hh:mm:ss"
End With
End If
Next c