How to add values to the last row and to the right?

Question

I have been working on a spreadsheet containing a table. I have made a code with inputbox that add new data to my table in column B and C. I am wondering how I, in addition, can add data to a third column that increase the value by 3 based on column C. Whatever I enter into column C, I want the corresponding cell in column D to be thrice as much.

    Public Sub InsertCargoNumber3()
Dim aaa As String, ar As Long
aaa = InputBox("Enter cargo number")

If aaa = "" Then
    Exit Sub
Else
    ar = Range("B" & Rows.Count).End(xlUp).Row + 1
    Range("b" & ar).Value = aaa
End If

Dim bbb As String, br As Long
bbb = InputBox("Enter Laycan Start Date")

If bbb = "" Then
    Exit Sub
Else
    br = Range("B" & Rows.Count).End(xlUp).Row
    Range("c" & br).Value = bbb

End Sub

Let's say in column C via the inputbox I enter 23.02.20, then in column D it should read 25.02.20

in advance, thanks

Answer 1

Please try this code.

Public Sub InsertCargoNumber3()

    Dim aaa As String
    Dim ar As Long


    aaa = InputBox("Enter cargo number")
    If Len(aaa) Then
        ar = Cells(Rows.Count, "B").End(xlUp).Row + 1
        Cells(ar, "B").Value = aaa

        aaa = InputBox("Enter Laycan Start Date")
        If Len(aaa) Then
            Cells(ar, "C").Value = aaa
            Cells(ar, "D").Value = Val(aaa) * 3
        End If
    End If
End Sub

Note that Subs and Functions are Public by default. It's when they are Private that they are special.

If the second aaa is a date, multiplying that number with 3 must give a date far into the future but if you want that number formatted as a date I recommend to exchange the last line of code in the above procedure to be replaced with this.

With Cells(ar, "D")
    .Value = Val(aaa) * 3
    .NumberFormat = "dd-mm-yyyy"      ' or whatever format you prefer
End With

Frankly, I haven't considered that you intend to enter a date there - perhaps because the following multiplication. Had I done so, I would have constructed the second input differently, perhaps like this.

' aaa has a value from previous use
do While Len(aaa)
    aaa = InputBox("Enter Laycan Start Date")
    If IsDate(aaa) Then
        Cells(ar, "C").Value = DateSerial(aaa)
        Cells(ar, "D").Value = DateSerial(aaa) * 3
        Range(Cells(ar, "C"), Cells(ar, "D")).Numberformat = "dd-mm-yyyy"
        Exit do
    End If
Loop