sprintf doesn't quite work - it can only handle whatever the underlying perl library handles natively: 

$ perl5.8.6 -MMath::BigInt -e '$i = Math::BigInt->new("123_456_789_000
+_000"); printf "%025d\n", $i'
-000000000000000000000001

[download]
The next best thing I can think of is: 
$ perl5.8.6 -MMath::BigInt -e '$i = Math::BigInt->new("123_456_789_000
+_000"); $s = $i->bstr(); $s = '0' x (25 - length $s) . $s; print $s,$
+/'
0000000000123456789000000

[download]
Note that this does the right thing if the string is already longer than you want, e.g.: 
$ perl5.8.6 -MMath::BigInt -e '$i = Math::BigInt->new("123_456_789_000
+_000"); $s = $i->bstr(); $s = '0' x (10 - length $s) . $s; print $s,$
+/'
123456789000000

[download]
Hope that helps.

In reply to Re^2: Math::BigInt and Leading Zeros by Tanktalus
in thread Math::BigInt and Leading Zeros by aplonis

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