From your description, I think something like this should work:

... 

my $number = 5038062; # In your example
my ( $grabbed ) = $var =~ /([0-9]{7})/;

print "$grabbed\n";

...
[download]

Given the number assinged to the $number variable, you will be able to capture any of the first seven numbers, 0-9, and placed into the $grabbed element. This approach will return a result set as an array, therefore the parenthases are required.

Another approach would be something like:

... 

my $number = 5038062; # In your example
my ( $grabbed ) = $var =~ /(\d{7})/;

print "$grabbed\n";

...
[download]

Where you are being less strict (kind-of) with the numbers, and are now requesting to capture the first seven digits (\d) rather than the first seven digits, 0-9.

I hope this is what you were looking for... and good luck!