Andi,

Myrna Larson to the rescue.... below is her classic post on the subject.

HTH,
Bernie
MS Excel MVP

You could use a custom VBA function to convert the base. The one below will
handle decimal integers with up to 15 digits, and can convert to any base
from
2 through 36.

Be forewarned, this is considerably slower than using the built-in functions
in the ATP, but it does handle a wider range for binary. (ATP is limited to
0-511, 10 bits).

The syntax for binary is =ConvertToBase(A1,2)
Octal, =ConvertToBase(A1,8)
Hex, =ConvertToBase(A1,16)

etc.


Function ConvertToBase(ByVal lValue As Variant, iBase As Integer) _
As String

Const sDigits = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Const MaxLen = 56
Dim IsNeg As Boolean
Dim sNumber As String
Dim p As Integer
Dim iDigit As Integer
Dim PrevValue As Variant

'Trap base value errors
If (iBase 36) Or (iBase < 2) Then Exit Function

IsNeg = False
If lValue < 0 Then
IsNeg = True
lValue = -lValue
End If

sNumber = String$(MaxLen, "0")
p = MaxLen + 1

Do While lValue 0
PrevValue = lValue
lValue = Int(lValue / iBase)
iDigit = PrevValue - lValue * iBase
p = p - 1
If iDigit Then Mid$(sNumber, p, 1) = Mid$(sDigits, iDigit, 1)
Loop

If p MaxLen Then p = p - 1

If IsNeg Then
p = p - 1
Mid$(sNumber, p, 1) = "-"
End If

ConvertToBase = Mid$(sNumber, p)
End Function 'ConvertToBase



"Andibevan" wrote in message
...
Hi All,

As far as I understand the standard Bin2Dec and Dec2Bin functions can only
handle 10 character binary numbers.

Does anyone have any pointers on how to handle binary numbers greater than
this?

If I have completely mis-understood how excel handles binary numbers feel
free to let me know.

Andi