B4J Question BCD code

Sub AppStart (Args() As String)
    Log(ToBCD(150))
    Log(FromBCD("000101010000"))
End Sub

Public Sub ToBCD (n As Int) As String
    Dim sb As StringBuilder
    sb.Initialize
    Do While n > 0
        Dim d As Int = n Mod 10
        sb.Insert(0, ToHex(d, 4))
        n = n / 10
    Loop
    Return sb.ToString
End Sub

Public Sub FromBCD(bcd As String) As Int
    Dim n As Int
    For i = 0 To bcd.Length - 4 Step 4
        n = n * 10 + Bit.ParseInt(bcd.SubString2(i, i + 4), 2)
    Next
    Return n
End Sub

Private Sub ToHex(n As Int, NumberOfDigits As Int) As String
    Dim res As String = Bit.ToBinaryString(n)
    Do While res.Length < NumberOfDigits
        res = "0" & res
    Loop
    Return res
End Sub