Extract numbers from Bios-Serial and make it four-digit

I need to get extracted the numbers from the bios serial string which I get using by:

wmic bios get serialnumber in [tag:cmd] or Get-WmiObject win32_bios | select Serialnumber in [tag:powershell].

Making the whole story a little more complicated the result has to be limited to four digits. In addition the result must use the rightmost digits of the serial.

eg.: A1G2S3W4B5 -> 1**2345**

If the serial does not contain 4 numbers the missing digits shall be filled by zeros.

Do you have any ideas or solutions on how to achieve this in command shell or PowerShell?

My minimal basic idea is to pipe the result of the serial query to findstr or something like that and sorting the numbers...

Thanks in advice,<br>
Chris

Here is one way to do it, first it removes any non-digit char from the string, then it removes all digits except the last 4 (assuming there could be more than 4) and lastly it adds left zero-padding using .PadLeft. If you wanted the padding to be on the right side, the use $result.PadRight(4, '0') instead:

$result = (Get-CimInstance win32_bios).SerialNumber -replace '\D' -replace '\d*(?=\d{4}$)'
$result.PadLeft(4, '0')

Adding some examples to see how it looks:

@(
    'AG0123SW4B5'
    '1AG12SW4B5'
    'FOOBARBAZ'
    'FOO1BAR2BAZ'
) | ForEach-Object {
    $result = $_ -replace '\D' -replace '\d+(?=\d{4}$)'
    $result.PadLeft(4, '0')
}

This results in:

2345
1245
0000
0012